I thought I'd run into a bug, until the next level used it as a game mechanic! Very charming little pixel platformer. There were a few problems, such as the breakable blocks on level 3-10 not being easily discernible from the environment, as well as a few levels that were more designed for players with the developer's level of skill at the game (rather than the player's), but overall a pretty solid game.
I will say though, the final level needs a wall on the right side of the staircase of pressure plates you need to climb.... It prevents players from jumping into a spot that they can't then jump to the next floor up from. Replaying the final "boss" isn't very fun. Also, please change "sliding" so that it only happens when the player actually has a direction key held down...