Making all different class combiations and leveling them to as high as possible just keeps me entertained to no end. Plus the whole difficulty lvl thing is what keeps me interested as well (clear the game on normal with a character, move to epic. Clear on epic, move to Legendary. Create a new character and you have to do it al over again for that character).
That's pretty much exactly why it keeps me playing, too. Each class by itself is as fleshed out as what you'd find in most games, but being able to mix and match them lets you try out a ton of different things and come up with wildly different ways to play. It's sort of similar to how changing map and ship types and minor factions can turn AI War almost into a completely different game, and you keep discovering surprising/fun new combinations even after playing for what seems like forever.
The completely static game world/content does make the multiple difficulties and starting new characters get a little tedious, though. It wouldn't be a problem that it doesn't change if it just weren't so
long. Unless you do something like use Deflier to cheat and start a new character at level 35 on Epic, it takes a long, long time trudging through stuff you've already seen and done repeatedly before getting to the point that you get to play with your new stuff much.
The bosses are always fun, and some of the areas/levels are, but half of them just get boring. Sometimes I never make it past Act 1 because I've already gone through it so many times, and you can't even sprint through stuff like the labyrinth to save time because there are no shortcuts. Basically, as much fun as the gameplay is, the pacing is terrible at times. If I were less lazy, I'd make a custom map that removes half the content but gives you twice the experience and hope it's somehow balanced or something.
Go look at Grim Dawn if you haven't already, by the way. Some of the guys who worked on TQ started a new company (after the old one went out of business) and are making a new game using an improved version of the engine, complete with all the multiclassing stuff.
It actually is sort of on topic, though -- it's really useful and interesting for me to hear why you love other games that are somewhat similar to AVWW. Not so that we can take their mechanics or whatever -- we already have our own ideas about that -- but because it's viable to hear "user stories" that were particularly fun, to use the technical jargon. Keith and I each know what sort of carrots keep us motivated and coming back to a game, but it's interesting and probably important to be thinking in terms of broader types of carrots than just what works on the two of us. Having that sort of feedback on AI War post-1.0 is what has really let it shine, I think.
I had sort of meant to address that more directly, but it seems to have gotten mixed up into what I already said above. I hadn't really consciously considered before that some of what I like about TQ and AI War is the same, despite them being completely different genres. I did already know that that's something I tend to like, though, and have sought out at times in games I play or included in things I've worked on.
Having many interacting systems or gameplay options gives people a lot of ways to approach things and seems like it can appeal to different types of people (as long as it's not so overwhelmingly complex that it scares most of them off before they learn to appreciate it, which does happen with AI War sometimes, unfortunately). Some of them like to figure out all the details of how they work. Some of them like to figure out what the "optimal" way of doing things is and what the strongest combinations are. I do some of both of those, but I also like finding things that are unexpected. There's just something satisfying about finding a weird/unusual but not buggy interaction between two (or more) things that make a class or playstyle that was previously thought to be unplayably bad actually viable (although not necessarily "good"). I've been known to do stupid things like solo a game with a character that
only has group-based abilities, just to show that it's possible, and figuring out how is sometimes more fun than actually doing it.