Very clever! I like the gameplay and objectives, it's a great use of chess moves.
It would be great if you weren't allowed to kill yourself since the game already tells you what moves will kill you, it's really just a matter of making a mistake or miss clicking. It's especially important because there's a few gotchas that aren't entirely obvious, like the fact that enemies can move through other enemies. Since they move simultaneously this makes sense, but is unintuitive if you think of it as chess. Also that the 'x' on an enemies tile implies that another piece covers that tile (which in hindsight is obvious, but is also easy to miss).