Really cool game idea. Sadly, I was born without a brain, so I was barely able to scrape by on the first stage, and was soundly defeated on the second, but it's clearly a smart design for those who are good at chess.
A small nitpick is that the game almost exclusively uses the mouse, but at random times I have to press enter on the keyboard. Let me click to select my stage! :)
Nice work and looking forward to future developments. Also, curious, which game engine is this running on?