Glad you had fun! :)
Yes looking back at it the difficulty is more suited for the developer than the player unfortunately. There wasn't time to implement an ending level so the game kept adding levels in the level select, hence it crashed when it found no new level. There might be a bug when selecting next level then, but it is the intended order (altough it could have been more thought out), some levels are just too hard. And multiplayer is a really good idea.
Thank you very much for your comment! I hope you enjoyed playing it :)