The graphics are very slick; I know retro graphics can be difficult to make distinct from a stylistic perspective but I think you nailed it here. The game is really fun and compelling; I wanted to see the rest of the levels once I got started.
The only thing that I have a problem with is the toggle button for dashing. Making it the "Z" key makes the game artificially more difficult than it needs to be. Maybe map it to "F" or a key more easily accessed?
Still, great job! :)
Edit: Yes, I was using the AD keys for movement.