Work flawlessly on linux and got a great time with. I got stock at the level where the crate should confuse bear...and yes I was confuse with it.
A great thumb ups for the pixel art, this is gorgeous, it remind me a lot of Jazz Jackrabbit (I don't know why). Music is great too.
Maybe the only improve I could think of, would be to implement a little tutorial. Even if the visual help a lot to understand, I took me some times to get some of the core gameplay element.
Keep the good work !