Oooh. This is a really cool mechanic. Unfortunately, I played it on a laptop, which means the jumping tricks are almost impossible to do with a trackpad. I wish that the slowdown thing would also slow down the bullets... And maybe last a little longer, I dunno. Maybe I should just go get a mouse :P
Pretty decent music as well. And good job creating all those sprites.
The tutorial backgrounds are really cool :)
Some of the tiles with computers (?) on them and a much lighter grey background were a bit confusing... I thought they were walls while they we're actually a background. Anyway, just a minor thing :)