I stand with the excellent regicidal duelling robots of Hats Are Not Allowed

This is just superb.

I'm not a fan of most fighting games. All too often they have too many elaborate moves, too much memory testing, or they feel like glorified puzzles you have to figure out the one solution to.

Hats Are Not Allowed takes an approach I find far more interesting. Combat is pared down to a few basic principles, and the challenge comes from learning how to combine them, and timing is less about animations than about second guessing your opponent. I can't say it's one of the best dueling games ever, but it's the best one I've played for ages.