Hi, thanks a lot for playing and for leaving a comment, this is great!
A friend I asked to play the game had similar feedback, they only got as far as level 4. I actually thought the game wasn't challenging enough when I playtested it myself, but I think that may be because I played games like Supaplex or Bomberman a lot when I was a kid, and they had similar logic to the monster movements. Next time when making a game like this I will probably add in a few easy levels at the beginning, to give the player a chance to get into the groove of things
Again, thanks a lot for playing!