I liked the art, I always love one art with a very minimal color pallete. And it was an interesting concept, but the game could really use some more explanation and feedback. The how to play section is bit much and hard to remember everything, and I wasn't entirely sure what I was doing.
The moving the player to take control of a monster seems clunky and unnecessary, but that's probably because there is no selection marker. I couldn't tell when I had the player, a monster, or no one selected, and the unselection after every move was annoying. Sometimes I'd select the player, move to a monster to control it, and then try to move it to another monster but then accidently click the monster instead and move it.
Once I got the hang of it, it was more fun, but one hero is totally capable of wiping you out because they can jump and kill monsters faster than I can move my hero and convert them.
Good job on completing the game! Good art and a good concept!