Undergrave reminds me a lot of Fights in Tight Spaces, which is a good thing. It's a turn-based fighting game where enemies move when you move, so if you move a tile, enemies move a tile, and if they end up next to you, you'll be hit - and you've got about eight hit-points so you can't take much punishment. If you die, it's back around again from the beginning.
There are no cards in the game, like in Fights in Tight Spaces, but you do have abilities. You can dash, jump, and throw your sword, assuming you have enough action points, and although they're powerful moves, there are drawbacks to using each one. Throw your sword and you have to go retrieve it, for example, and dash carelessly and you'll end up in trouble - you don't get to choose how many spaces you go.
Then again, you can dash through a line of enemies, which is incredibly satisfying. Like a samurai in a bamboo forest, you make your move and then watch as two halves of the enemies' bodies slide apart. It's also very satisfying to jump on someone's head, killing them if they're a weaker enemy, while pushing back and stunning enemies around you. Jump is great but it's an expensive ability to use.