Writing AI as part of gameplay Thread

For quite some time my mind is occupied with idea of making game based on competitive creation. By this I mean creating something, then using it against other player's creations. But what is the object of creation you ask. Kingdoms? Castles? Armies? Maybe one day, but the first thing we'll let them make is AI. Why that? Because in all games I've seen so far, be it RPG, shooter or strategy, it's unbelievable dumb, repetitive and predictable. Perfect accuracy and lighting quick decisions don't help in the long run. Neither randomness nor work of few developers can ever compete with user input in term or replayability.
Thus that simple prototype would be base, possibly open, for further developed games heavily dependent on NPCs.

The most basic version should consist top down real time arena fight between two NPCs (circles that can move, rotate and shoot short range strikes, like RotMG melee units) and graphical, user friendly AI creator. How can such fight be interesting? With so few variables not too much, but we'll be slowly adding new options that can be used by AI, amongst them:
1. Interia and direction based movement, so changing direction and rotating is not instant, and walking backward is way slower than running forward
2. Blocking, based on angle from which attack come from, 100% chance from front gradually decreasing to 0% at sides
3. Various kinds of attack, long range straight stab, side slash that come from different point than stab, short range pushing shield bash, etc.
4. Weapon to weapon interaction, so hitting enemy strike with yours changes it's direction
5. Hits that posh or turn target, so well placed hit, even if it doesn't do any damage, can expose weak spot
6. More NPC on arena, so formation AI can be created too
7. Various equipment, from versatile sword, through devastating axe, stunning mace, long spear to two handed toys.
8. Elevation as element that gives some combat advantage.
9. Player controlled character, to finnaly check how long it takes to learn and beat AI tactics.

I'll write more details and examples later. Now I invite you to discussion. Maybe you know existing project with such principles? Maybe you've tried? Maybe you know existing engine where it could be easily tested?
Share your knowledge and opinion.