Redesigning Health and Mana.

[x4000]

Hey all, this is something I've been working on for a while, but it's something that is hard to talk with Keith about at our usual design level because he's simply never played Metroid, Castlevania, or even much Zelda.  Just not his sort of games.  So I'm going to bounce these ideas off the forum instead, where there's loads of smart people with the right backgrounds in gaming to be able to think about this and what's worked well  or poorly in other games.

The Problem
The current system for health and mana is the same in both cases: you have a certain max numeric amount of each.  They also then have large amounts of restoration items that you can carry along with yourself, and which even get auto-used when you are low.  So really what we have is health and mana restoration objects as an extension of your base health/mana bars.

This is problematic for several reasons:

1. It means that really to know your "total health" requires knowing your total number of health potions and their various levels.  To get that info would either require you to open the inventory, to keep those on your ability bar (wasting space), or for us to develop a new element in the HUD, which I think would just be clutter and confusion.

2. It means that you can essentially carry around near-infinite stores of health and mana.  The only limiting factors are how many you are willing to wander around and thus collect, plus the cooldown-that-lasts-twenty-seconds thing that means that you can only absorb so much damage in a short amount of time.

3. Thanks to that cooldown you wind up dying if you're overmatched no matter how many health potions you've got in your inventory, which is a positive thing on some levels and a negative thing on others.  On the one hand it means you can't just become invincible by collecting a thousand health potions, but on the other hand it means that your ability to be a damage sponge is pretty limited -- there's not much flexibility in that system.

4. All of this combined means that we really can't give warnings (visual or auditory or both) when you are low on health or mana.  In Metroid or Zelda, you get both kinds of warnings and that's really helpful because you know you're about to die.  Yes, in Zelda you have fairies in bottles that can bring you back to life automatically, but you still die, go through the animation, and most importantly only have a REALLY finite number of fairies (usually 3-4 max).  But in AVWW, you might have the equivalent of 100 "fairies" of various levels in your inventory, with restrictions that you can't use them unless the healing cooldown is free.  That is SUPER difficult for the game (or the player) to really be able to intuitively answer the question "am I about to die if I take another few hits?"  The answer is often something conditional like "yes if it happens in the next 4 seconds, no if it happens after that."



All of this is striking me as needlessly complex and confusing, basically.  A lot of the problems here came about because I implemented lots of streamlining suggestions from players -- such as auto-potioning, etc -- which were all really great suggestions, I might add.  But collectively these suggestions plus the original design have combined to expose the weakness in the underlying design.  To me, that means it's time for a fundamental shift.

Things We Know
Based on all the player feedback on the existing system, plus looking at other games, a few things seem pretty clear to me.  They are:

1. Manually having to take time out to heal yourself in a game that is as action-oriented as this feels lame.

2. Systems of regenerating health generally are thought of as pretty lame, and really wouldn't fit with the nature of this game.  (Side note: Arguably, the current cooldown system on healing is sort of an unusual "regenerating health" mechanic, because you HAVE more health that you just can't use until a time limit has passed.  The only difference here is that you have to manually collect your potions that do the regenerating, rather than having an infinite supply of regenerators.  I just thought that was interesting.)

3. Having to periodically go and collect stashes of health and mana potions is... mixed.  Some people really like that, and it certainly does give purpose to the small buildings, but it seems like something else that is more optional-and-exiting would do better to collect there.

4. Health drops from minor enemies have been a particularly universal hit.

5. Players past a certain skill/familiarity with the game definitely seem to want more visibility into what is going on with their total health and mana situation than they can currently get through the HUD alone.

6. Adding lots of extra numbers and bars and icons to the HUD will just clutter things up and make the system that much less intuitive for new players.

What Is The Overall Design Goal Here?
Why even have health and mana at all?  What is their actual purpose?  I think it's important to define the specific reasons for their inclusion, since there are a lot of varied reasons that any game includes such mechanics (and why regenerating health works for some games but not others).  So here's my list:

1. Health is important for making players feel vulnerable and alone in this world.  They should have a finite store of health, and when that health runs out they know they are dead meat.  (Side note: Ideally they feel really out in the wild and at risk when they are exploring, but the whole mechanic of warp potions kind of kills that, which is ultimately okay since it's preferable to the backtracking nightmare that otherwise exists).

2. Health is important for making mistakes matter.  Overall you shouldn't be dying in a single hit from an enemy unless you are playing way up in levels, and in that scenario that's probably the scenario you were looking for (I know I enjoy that).  But in terms of standard gameplay at default levels, your character's death should be the accumulated consequences of a number of mistakes, not a single missed twitch reflex (though that missed twitch reflex of course might be the last mistake that pushes your character to death, of course).

3. Health restoration as a concept is, in the context of this game and most platformers, NOT something that players are intended to be able to hoard in order to get past a difficult area they could otherwise not pass.  That works in some RPGs because of their turn-based nature and the opportunity costs of using something like an Elixer in Final Fantasy (it takes a turn, and Elixers are limited in the whole game).  But for this action game, if you can't get past a difficult section then what you need to do is either level up or turn down the difficulty.  If weaker players can spam healing to survive big bosses, then stronger players could do the same thing to "run the tables" so to speak.  We ran into that sort of mechanic exploit cycle a lot with AI War in the early days, and have learned to stay away from that now.

4. Mana is important for making there be an opportunity cost to using spells.  If a spell is really powerful but also really expensive in mana, then you have to weigh that against weaker-but-cheaper spells.  This is hugely important for balance of the player side of this game.

5. Mana is also important, like health, for limiting the length of expeditions and making it so that you have to return to settlements every so often to re-kit and prepare for a new expedition.  There's a fine line, though, between returning too often and not often enough.  Players should be self-sufficient in the field for a goodly while, but not forever.  There's a lot of thematic and gameplay reasons for that, but I don't really wish to enumerate them all right at the moment (this is long enough already!).

My Broad Concept For Fixing The Problem
Overall, what I think needs to happen is that the health and mana bars on the existing HUD need to contain all the information you'll ever need about your health.  The original Metroid really did this correctly, I feel.  For instance, there you had your energy tanks and your actual energy count, plus your count of things like missiles, etc.  Zelda games kind of do this as well, although not as effectively because you do have bottles of various restoration items; the catch is that since there are at most four bottles, you can easily remember what you have in stock most of the time.  Not so here at the moment.

So, broadly speaking, I feel like healing and mana items in your inventory need to go away, and their general concept needs to be wrapped into your main health bar and mana bar in some fashion.  There are a lot of ways that could be interpreted: the wholesale copying of the energy tank model from Metroid, the health + shield model from a lot of other games, or similar.

My Current Favorite Solution
What I like the best, I think, is just keeping the health and mana to a single numeric bar each like they are now, but having it so that there are basically two "maxes" in there.  I'm not sure exactly how to word this or even show it, but basically "full health" would be 100% of your bar at first.  Then as you travel around and get health upgrades, you'd wind up with a progressively higher max health.

Getting "restored to full health" would still only restore you to the equivalent of your first maximum, though, at any point in the game.  That's like getting just your first energy tank restored in Metroid.  It's also like getting restored to full health at present, but not getting your "potions" restored.

The general consequences of this model is that then:

1. "Potions" are carried directly in your health bar, but you only have so many of them depending on how upgraded your character has gotten.

2. "Potions" can be restored by efficiently fighting mobs, since any sort of healing that wasn't "restore all the way to max health" (read: the guardian stones) would be perfectly able to push your health higher than your original max health.

3. Stashes would still have value in terms of mana/healing, because you'd still be able to pick up potions in large quantities there.  The difference would be that potions would ONLY be insta-use, applying to your health bar, and would never be able to be carried around in your inventory.

4. "Getting fully healed by the guardian stone" would really get devalued enormously over time, because if your true max is now 8x what your original max was, and you're not lower than 1/8th health then the guardian stones won't help you at all.

5. Oh, and mana would work the same as health.


The terminology and the actual display mechanism isn't the cleanest at the moment, which is the main problem I think.  The energy tank model of Metroid really is a lot more clear while doing the EXACT same thing, so possibly I should just stick with that sort of terminology.  "Health tanks" and "Mana tanks" or something along those lines, being shown above your current health/mana bars.



Thoughts?

[tigersfan]

I like the health tank idea, but, it seems odd to me as a mana mechanic. Honestly, I'm not sure we even need much of a change for mana. How about these changes:

1. Have mana slowly increase if you don't use it. The idea being like in many Fantasy realms that mana comes from an internal source of energy, so using it will tire you out, but, as you rest, it goes up.

2. Obviously, there needs to be some way to increase it mid-fight if you run out. So go ahead and keep the potions, but make them MUCH more rare. Maybe only slightly more common than the warp potions are right now? Also, so you can keep it all on the screen, maybe limit them to 5 or something, and they can light up above the mana bar or something.

3.  Get rid of the mechanic that automatically pops mana potions for you. This makes you have to put some thought into what spells you cast as you get low, and maybe even add a period of time (short, 5-8 seconds or something like that) where you can't cast ANY spells after you pop the potion. This makes it so that popping a potion is a tactical choice, not taken lightly.

[zebramatt]

Would there be a maximum limit to the number of health tanks?

[x4000]

1. Have mana slowly increase if you don't use it. The idea being like in many Fantasy realms that mana comes from an internal source of energy, so using it will tire you out, but, as you rest, it goes up.

Well, the one thing that Keith and I have definitely always agreed upon is that "just sitting around and waiting" should never be a valid gameplay mechanic.  If we're incentivizing players to just go out into a boss fight and use Mega Awesome Spell, then retreat to a corner and wait 3-5 minutes while their mana restores so that they can pop out and case Mega Awesome again, then some players will do that and complain about the grind to us.  See knowledge raiding in AI War as a classic example of this.

2. Obviously, there needs to be some way to increase it mid-fight if you run out. So go ahead and keep the potions, but make them MUCH more rare. Maybe only slightly more common than the warp potions are right now? Also, so you can keep it all on the screen, maybe limit them to 5 or something, and they can light up above the mana bar or something.

Here again, making something "more rare" doesn't really help.  The only thing that actually helps is having an inventory cap on this sort of thing.  If a player can ONLY carry a small number of mana potions then they have to strategize their loadout.  Like Zelda, although in that case it's a mix of limited health AND mana restoration slots, so there's actually some choice.  Or would be if magic wasn't pretty useless in those games for the most part.

The thing is, once again, if we make mana potions rare and hard to get, players will still want tons of them -- and then they'll complain that it's boring to go and get them.  The only solutions to that which I've ever found are to either not have the coveted thing, or to have a very firm cap on how many of that coveted thing the player can collect.  Or to make it so unbelievably difficult to get the thing that only someone who has no other option to proceed at all in the game would ever try it.  That last worked with knowledge raiding, but it doesn't really make sense here because we need a general mana mechanic and not something to help players who are stuck (they can always level up or down the difficulty, they don't need extra mana).

3.  Get rid of the mechanic that automatically pops mana potions for you. This makes you have to put some thought into what spells you cast as you get low, and maybe even add a period of time (short, 5-8 seconds or something like that) where you can't cast ANY spells after you pop the potion. This makes it so that popping a potion is a tactical choice, not taken lightly.

See, but all this does is require players to waste an ability bar slot or remember to hit this button periodically.  And it creates this period of time where players just have to sit there, unable to take actions of any sort.  The general goals of mana are to require players to conserve and manage their resources, but having to periodically use some sort of secondary slowing-down action isn't really a requirement.  I think that's the reason a lot of FPS games have been moving to not having you ever reload, just having a number of bullets per gun type and that's it.  Others obviously still use reloading, but in the main the weapons tend to reload faster than they used to unless it's a really BFG type weapon.


There's a limit to how many variables a player can judge at once, and streamlining the health and mana displays so that it's all onscreen and not requiring interaction from you during battles is something that I feel like makes a lot of sense.  You're there with whatever you brought, and now it's time to manage your spells and your tactical position and watch the enemy's tells and dodge projectiles and choose what spells you fire, etc.  Managing your healing and your mana on top of that seems like too much, and also like the least fun parts of an encounter in this game, especially given its really fast pace compared to WoW or similar.

Not that I'm hugely sold on the energy tank thing for mana, but there is something to be said for consistency.  And it does have some advantages.  I'd been thinking that some sort of slow regen for mana might also be nice, but then again that's encouraging waiting around.  Instead of a slow regen to regain mana, you could always use non-mana-using spells or scrolls to fight when your mana runs out, or you could use those non-mana-using abilities to kill small mobs for mana restoration.  Which then gives a harder choice to the "do I leave the monster spawners or kill them" decision in boss rooms.

[x4000]

Would there be a maximum limit to the number of health tanks?

Very definitely.  Getting a single tank would be a Really Big Deal, and the limit would probably be something like 8 or something along those lines.

[Toll]

As for mana regeneration... While I wouldn't mind a constant slow mana regeneration, having it as the only option other than mana potions would really suck, if mana potions became rarer. It'd just lead to the dreaded DownTime. One solution to this would be a "meditation mode" or some such, that would only work in certain circumstances (haven't used mana in X seconds, haven't been hit in X seconds, and/or no enemies in your immediate vicinity) that would boost the regeneration massively, to a degree that would let you regenerate your mana supply in perhaps ten seconds. The limitations would ensure that you can't fight a boss, run behind a wall to meditate and then come out blasting again.

[zebramatt]

Reading through the above, I did have one idea along similar lines...

You have your "health" (as now) and an additional "health flask" (an initially empty icon to the side of your health). As you collect health "potions" in the world they fill up your health first, then your flask - with different relative tier potions filling it up less or more, as now.

In addition, at any time you can manually top up your health from your flask. Perhaps this is a hold-to-fill activity; perhaps it simply restores you to max and drains the equivalent from your flask. On death, maybe you need a full flask to survive, maybe your entire flask is drained but you only get max health - or maybe another item is introduced altogether to save you from death...

As you progress, or triggered by certain events, the "tier" of your flask increases - meaning a greater capacity for the most part, but also perhaps new abilities later on, such as saving you from death.

Max health restoration from guardians would fill your health but not your flask.

It's a different spin on the health tanks idea, anyway, and I think it works to all of your points above...

[Penumbra]

Having a limited number of health tanks sounds like a great idea. I have been playing Dark Souls recently, and it has a mechanic where you have a refiling health potion with 5-20 charges in it (depending on different situations) and they serve as a "how far can you go" meter. Giving the player a well defined limit on the amount of mistakes they can make before returning home. That game has a ton of backtracking in it, but their potion system works well.  Health in AVWW is the strategic resource of how long you can adventure for.

As for mana, it should be a tactical resource, as was mentioned earlier. But, tactical situations don't last very long. Fighting a group of monsters takes, maybe, 30 seconds at the most before a player could get themselves. What if, instead of mana being a pool that spells take away from, it instead worked as an "overheating" mechanic. Certain small spells would cause little heat, and larger spells would cause more. It would take no more than 5-10 seconds to refresh fully. A sliding scale of cooling off that increases by not casting spells. This would let the playing decide how much to take on at once in much smaller chunks.

I would have my health points to worry about for my long term planning, but my mana can be for the short term.


As for resource gathering, I know that my personal play style changes from "I want to make progress" to "I need to stock up on things." A player who wants to spend more time stocking up might feel limited in only being able to hold so many on them at once while not being able to put more effort into gathering. What if the guardian stones could store twice the number of potions you could carry with you. Then, you could cache a few of the ones you have the next time you hit a stone.

[TNSe]

I really like the current system.


That said, I did like the Metroid system. Maybe it can be combined with current system.
- Each "tank" holds as much life as your life bar max.
- Once your life hits <0, an entire tank is emptied into your life, subtracting damage beyond what put you at <0 health.  This has a 10 second cooldown. If you drop <0 again during these 10 seconds, you die.
- Your life continously fills up with 5% every second. (That means you hide for max 20 seconds, although normally you are fit to fight after 10 seconds.)
- Number of tanks is not limited.
- This gives you more of a hit and run along with pretty good sustainability for when you are good at evading damage.

For mana:
- Drop it. Limited resources for damage is not fun.
- Use cooldowns.
- Use combos.
- Add charge up skills and finisher skills.
- Examples:
 Fire Touch: Deals X damage, and additionally deals X more damage for each stack of "Fire Power" you have.
 Fireball: Deals X damage. Adds one stack of "Fire Power"
 Circle of Fire: Deals X damage. Adds one stack of "Fire Power" for each enemy target hit.
 "Fire Power" is limited to 3 stacks, and is cancelled by "Water Power" or Water damage taken.
 (Fire Power could be shown as a red fire circling the player)
 Tidal Pulse: Deals X damage, and additionally deals X more damage for each stack of "Water Power" you have.
 Ice Cross: Deals X damage. Adds one stack of "Water Power" for each enemy target hit.
 Splash Back: Deals X damage. Adds one stack of "Water Power" for each enemy target hit.
 "Water Power" is limited to 3 stacks, and is cancelled by "Fire Power" or Fire damage taken.
 (Water Power could be shown as water flowing around the player, sorta like the invincibility lightning)

 Obviously spells would need retuning, mostly in the cooldown department.

 This would get even more interesting when you start making spells that can deal multiple damage types, like:
 Meteor : Deals X Fire and Earth damage (whichever deals most after resistances), addtionally deals X more Fire damage for each "Fire Power" and X more Earth damage for each "Earth Power".

[Underfot]

Another option is to skip the flask/tank graphic entirely and use the existing health bar with a percentage.  Guardians would heal you up to 100%, potions and mini drops could take you to 200 or 300%; perhaps more with special items. 
If you are anywhere above 100% health, the bar would be full length; perhaps it could change shades as you approach 200 or 300%.  Once you drop below 100% it scales normally to let you know you're in trouble.

I'm not sure I would change mana in the same way.  It seems to me that before you enter a major fight you can take stock of your health and try to regulate how much damage you take.  You can't do quite the same with mana because room layout and enemy type will influence your spell choices.  I've had to retreat from fights after running out of mana and potions; it never feels quite as satisfying as escaping with the last scraps of your health.  Limiting mana could also lean the game towards 'making every shot count', not necessarily a bad thing, but not my preference.  I would suggest leaving the option to stockpile mana potions. 

[FallingStar]

I'll toss in some thoughts as well, I'm not sure any of them are fully formed as its off the cuff but perhaps it will help.  I agree with a lot of the thoughts, and think a change is for the best, but my meandering thinking:

On the OP "current fav" system - I think if implemented as stated, the shift would be that between every major thing I wanted to do (grab gems, fight boss, etc) I would feel like I needed to "fill up." Players like to be on full tankyness, especially with permadeath involved (even if its not world ending).  Killing trash mobs isn't consistent, so it would likely mean entering every building in a chunk up to the location of said thing I'm wanting to do, grabbing stash, rinse and repeat until full.  It feels more farme-y in my mind, even if it may not be in reality.

The one advantage of the current system is that, rather like gem runs and spell tiers, you don't have to do it all the time, and you largely do it while grabbing things that you already want to get (mostly gem runs for me).  You could grab dust to make 100 heal scrolls/ mana and be good for 10 or more levels if you don't play poorly.  Its just that psychological thing of feeling like "I could tank more so I need to go grab a stash" all the time vs feeling like you have a good buffer, and sometimes being wrong, but if you need more you're also grabbing other things you need at the same time.


Some other random thoughts I had while reading:

1) There's two kinds of fighting in the game.  Trash mobs (exploring), and bosses (all types).  Because you never have to kill a trash mob, and it gives you nothing other than the possibility of a small heal / shard (/coin -kind of Zeldaish as I think of it) . . .well it makes me think that there's little need for an active/extra heal during exploration.  As is, I certainly use some, but I also explore higher chunks and storm dash through anything and everything while holding the shield button. Not having tons of extra heals/ mana in exploring would make it feel more dangerous so long as some of the travel spells were tweaked to be more expensive/ hurt more for skipping over things.

2) Where you really need healing/lots of mana is the bosses.  That's where you can get fancy with the system.  Perhaps something where a special spell vs only bosses could be used (emphasizing why normal people can't do these things on their own) that adds extra tankyness/mana, or some such.  I don't know just seems like the fact that there's a duality in the types of fights might lead to something where out in the wild its  simple, just drops, then with bosses there's a bit of a twist to make the fight winnable /a bit more things to manage as part of the challenge.

3) I think shielding tweaks is the third leg of this, since depending on implementation that could be the tank in and of itself, and cut out other mechanics as needed.  As is, the shields are touchy and you need other tanks since especially playing up in chunks where shots come in very fast, and screen resolution means the reaction time to hit is almost nil, my tactic is often just to hold down shield button and hope it absorbs x number of hits to mitigate damage, or count in my mind the time between boss shots and hope I keep at Y range to make it constantly catch a few more shots.

I know there's been mention of longer term shield scrolls, which could help be the tank, and if the battle oriented short term shield could somehow be managed a bit better so it wasn't totally twitch/platformer skill, that could be a good boss tank.  It doesn't solve mana management unless shielding did all of that too, so I don't know if the idea is there yet . . .but it just seems like shields that are already in should also be part of the solution, and that if you're trying to consolidate the idea of "how much tank do I have?" in the player mind, this could be a big part of it.


Anyways, kind of long, but hopefully something good.  I'll give some more thinking to it, see if there's a more firm idea floating around somewhere.

[x4000]

A few thoughts:

1. Dropping mana entirely definitely isn't on the table.  That's how things were originally (pre-alpha) for the game, and it just doesn't work.  There's no way to have gradations of power like I want in that sort of system, and cooldowns alone just don't work.  The only way to have mega-spells would be to make them very limited-capacity spell scrolls, and that is something that already I plan to do some of, but there are psychological worries there as well because people are very wary of using up something like the scrolls that are gone-forever once used.  Mana is really nice because it's flexible and really fulfills a variety of gameplay goals (the feeling of having ammo among them).

2. It's true that people would want to have "full tanks" all the time if they could.  That's certainly how I play Metroid, and even something like Cave Story.  That's perhaps the hardest barrier to overcome with a more Metroid-style system.

3. Some of this does also play into other changes that would come for the game anyway, such as more shield spell/scroll options and things like trash mobs with way more health and danger to you.  Right now the trash mobs are something you can really ignore in most cases, but I think the Utahraptors are a good example of the way some mobs will become, where they are much more dangerous and something you really need to treat almost like a small boss fight as you progress across the terrain that they control.

4. Having unlimited healing items strikes me as a huge problem in general, whatever the system is.  It does scratch the hoarding itch in a positive way for players (like myself) who tend to that.  But it also creates a system where there HAS to be cooldowns on health potion use, which I don't really love for reasons I'll mention in a sec.

5. Having a system where you are required to use health potions manually when your health gets low, OR where you can't use your healing stuff because of a cooldown, is something I don't love.  It works for turn-based games like Final Fantasy because those are all about managing your actions and you have time to consider these sorts of things.  But in more of a Shmup-style action game like this, it's just going to make for lots of accidental deaths anytime you are somewhere legitimately dangerous.  That's part of why a lot of the mobs are so underpowered at the moment, because when they are more of a threat people die constantly from the healing mechanics.  I'd like to see much more substantial mobs after the first few levels of play in general, but right now I feel like the healing situation needs to be looked at first.

[Hearteater]

Regarding mana:

Health and mana are nearly identical mechanically.  Both limit your exploration in the same fashion.  The only real difference is you always spend mana, where as with health if you are skilled enough you might be able to avoid taking any damage for long stretches.  That said, I feel making mana function like health is redundant to a degree.  This is one of the reasons I really don't like old-school mana systems; newer designs have a better effect on gameplay.

Instead, consider making mana function more like energy in other games.  In other words, something with a fairly low maximum but very quick restoration.  Your super spells could blow through your energy very quickly leaving you with 5-10 seconds of dead time, or you could pace yourself with more reasonably costed spells.

Replace traditional mana potions with ones that "super-charge" your energy regen for a short period of time.  With their over-time nature they natural avoid issues of stacking.  No matter how many you have, you can't get mana back faster than the boosted rate.  For most bosses you'll probably only need one or two to last the entire fight.

Not to mention with this system you have two stats for mana.  Besides the maximum pool size you also have unboosted regeneration rate.

If you are concerned that skilled players will be able to progress too far without the constraint of mana, adding small bits of nearly-unavoidable damage from boss, lieutenants and such.

I'll post on health separately.

[Hearteater]

I like health tanks, and I especially like stones in the field healing you only to 100% (so not affecting health tanks at all).  The town stone may need to be stronger, since being forced back to town is somewhat pointless if you don't really get to "start over".  It may be the case that staying in the field is more beneficial than returning to town, which I don't think is good for players down to 75% health and no tanks.

The heal tanks themselves, however, might make more sense as "temporary" in the sense that you can lose them in the field.  Either from certain super boss attacks or after taking X amount of damage (say every time you take four times your base health in damage you lose a tank).  This would make collecting tanks something that is ongoing.

It might be worth considering making tanks have no maximum, but instead have them come from collecting X pieces of a tank.  To get your first tank requires 2 pieces.  Your second takes 4, third takes 8, and so on, doubling each time.  I'd still be able to collect the pieces and the decision on when to make them into a tank would in important.  For example, say I had 4 tanks.  I need 32 pieces, but I don't really want to waste that many on a tank, so I just save them for if I lose a tank in the field.  That way I can just replace a tank for 16 pieces.

From a flavor standpoint, I'm envisioning health tanks as fortification enchantments.

[Baleyg]

4. Mana is important for making there be an opportunity cost to using spells.  If a spell is really powerful but also really expensive in mana, then you have to weigh that against weaker-but-cheaper spells.  This is hugely important for balance of the player side of this game.

I would say that point 4 is really close to being correct but not quite.  If mana gets rebalanced so efficiency is actually a concern, there will be a single point of the efficiency-to-DPS curve that is optimal.  I don't think pushing the character towards a limited set of spells is desired.  The goal is to reward using a wide variety of spells, correct? 

Mana-based games sort of allow that, but only because the player blandly follows the cues of the game.  Fire vulnerable mobs show up and you switch to fire spells.  The player is using multiple spells, but probably only one of each element.  And it always feels like you're being led around by the nose.  The problem is that mana is too flexible.  You can spend a little mana to fire a magic bullet or a lot of mana to fire a magic rocket, and your decision is usually based on what's more effective.

But in action-horror games your choices are more constrained, and almost paradoxically you choose more.  You have strategic choices in which weapons to carry.  And you have tactical choices in which weapon to use in any given situation.  A lot of those choices hinge on that fact that each weapon has its own ammo pool.  You use your workhorse weapons most of the time, and switch to more powerful weapons as the situation gets more dangerous.  Bosses get hit with your most powerful weapons because you need them to die quickly, and because weapons that are overkill on most enemies are used to their full potential against the bosses.

So I would suggest tying spells to some sort of ammo system, where roughly equivalent spells use the same ammo or charges.  Each consciousness shard pickup in buildings could also restore a number of spell casts, but you probably don't want to tie colors to charge types.  I think that each pickup should restore a sizable number of basic casts and a chance at restoring more powerful casts up to a maximum charge limit.

Fire touch, fireball, forest rage, tidal pulse, and plasma bolt would be good candidates for unlimited shots.
Ball lightning, throw rock, energy pulse, miasma whip, and maybe Launch Meteor would be candidates for using the same basic ammo.
Creeping death, rockslide, and maybe meteor storm are fairly similar to each other and would be another grouping.
Ride the lightning, storm dash, storm rush (at a steady cost), and lesser teleport could be grouped.
Death touch, ring of fire, and ice cross could share a group with any future point blank spells.
Greater teleport would probably get to be smug and have its own pool for a while.

TLDR:
Toss out mana and replace it with ammo/charges.