Bug
This was nice, but I got stuck on a bug that was impossible to get out of without restarting the whole game... In the level with the hanged red 1, where you end by going down a ladder, the game jumped and I ended up at the bottom of the ladder. I couldn't climb back up or go in any direction, and for some reason the quit game button from the esc menu didn't respond either... Neither did the restart.
It is a shame because this was a nice little game but I couldn't be bothered to reload the whole thing