I like this a lot! it's less stressful to me than mamono mower (i think i'm used to a more slow and methodical minesweeper experience), but still provides an interesting and unusual challenge. I really like the different patterns that the different beasts create on the board.
It would be nice to have some kind of shortcut to mark different types of beasts! (For example, if typing 1 made your right clicks only monsters, 2 made them only slimes, and 3 made them all ghosts.) Clicking six times for a ghost is a lot.