First, Blade Module should be a sac-only item. Second, Secret/Sac rooms should not be opened by blowing up glowing blocks. That just removes the need for items that reveal their locations, which makes all those items/consumables/level-ups worthless.
All sac items need an improvement. Examples (3-5 health cost, sac-only unless noted):
Hyper-X Capacitor: Energy recharges constantly, but is drained to zero when entering a room.
Gold-Plated Battery: Adds credits to energy, sets credits to zero. (costs only 2 health, not exclusive to sac shop)
Platinum-Plated Battery: Adds credits to energy, halves credits.
Gift Box: Pops out 3-5 basic loot and 2-3 consumables when purchased. (costs only 2 health, not exclusive to sac shop)
Shotgun Missile Launcher: Fires 3 missiles in a shotgun pattern. Uses 3 ammo per shot.
Deadshot: +100% damage, bonus decreases 20% per shot (down to -20%...aka 80% of base). Recharges back to +100% when not firing (+10%/sec).
Aegis System/Module: Grants an orbital destructible shield whenever you enter a room (see the new enemy ship White Aegis in mantis/mod forum)
Chain Reaction: Your main weapon shots bounce (re-fire) to another nearby enemy after hitting an enemy ship. (Module)
Limit Breaker: Gain +100% fire rate and damage immunity for 3 seconds after killing 3 enemies in a room (once/room)
Shock Rounds*: Enemies hit at full health are stunned for .5 seconds (so the first hit on any non-boss enemy)
Freeze Rounds*: Enemy fire rate reduced by 20% for 3 seconds (maybe need an "immune to fire_rate_slows" flag on systems, or just make bosses immune naturally)
Petrifier: Enemies killed turn into "stone" after death, blocking shots. They take damage and break, just like the big blue blocks. Keeping momentum at death and bouncing off walls a plus. (stoned ships are grey-scaled, shader maybe?)
Mirror Armor: Immune to laser traps and moving threw a laser shots out a spray of bullets that hurt enemies. -20% damage from laser damage type.
Void Shields: When entering a room, you are immune to damage as long as you have shields up. You lose 1 shield/3 seconds (so Flame Mech would get 6 seconds of immunity/room, maybe color shield bar UI purple instead of blue)
Emergency Shield Generator: The first time you take health damage in a room, you gain 1 shield back (module).
Burning Shields: You deal damage to enemies around you while your shields are up. More shields up = more damage.
Death Ray (energy weapon): Slow ROF. Deals 5 damage per 1 energy. Spends exactly enough energy to kill target. You gain 10 energy whenever an enemy dies (for any reason).
Exotic Alloy Chassis: +4 max health, health pick-ups heal for half (not exclusive to sac shop)
Blood Money: Gain 1 max health per full 25 credits. Credits set to zero. All health pick-ups give 2 credits instead.
Cyber Vampire: Current health reduced to 1 at the start of each room. Gain 1 health for each enemy destroyed.
Other power-up suggestions (may or may not be modules):
Tank Treds: Immune to caltrop damage and movement slows.
Stealth Module: Enemy wake-up range decreased by 25 or 50%. +25% damage against enemies that are not awake.
Exploding Rounds*: Shots exploded on impact, dealing 10% of base damage in a small area around the target.
Chaff Launcher: When you are hit, sprays out random bullet-blocking projectiles that expire after a few seconds. Only triggers once every 5 seconds.
Power Diverter: +25% damage when you have no shields up.
Leg Stabilizer: Increase damage by 8% per second standing still, up to +40%. Resets when you move.
Buy One Get One Free: When you buy an item in a consumable shop, you get a duplicate free.
Omni Power Module: +100 energy, -20% energy costs. If you have all 3 omni items, all your damage increased by 25%.
Omni Cannon: Same as the white mech basic minigun, but gain 2 energy when you hit an enemy.
Omni Energy Beam: Narrow version of the incinerator, more attacker power, 40 energy/sec.
Second Wind: Heal to full when you level-up.
Threat Detector: You can tell a room is a mini-boss before entering (So the purple door and map icon for mini-bosses is gone without this. On Very Easy and Easy, you have this item for "free" though. A map of the level still reveals mini-bosses).
*Ammo: Maybe we could use an ammo slot, like for modules. Some weapons would use ammo, others (like the flame thrower) would not.
Consumables:
Box of X Ammo: Multiple items. Gives the effect of the X Rounds power-ups above (plus the poison ammo already in game), but only for the current room.
Time Bender: Slows all enemy ships and shots by 50% for 10 seconds.
Manufacturer Recall: Rerolls all items in your current shop.
I Am Your Father: Creates a clone of yourself that mirrors your movement and fires when you fire (orbitals not cloned, direction keys are reversed on clone). Last until you leave the room or it dies.
Sympathetic System Shutdown: All enemies in the room are set to your percentage of max health, and stunned for 0.5 seconds.
Extinction-Level Virus: Homing projectile that poisons the target for 75 damage/second over 5 seconds. When the target dies while the poison is active, three new homing shots fire from its wreckage. Also, do_not_stack="false".
