Hey thanks for playing the game, we're glad you liked it! I just double checked by playing through and the functionality is there. We probably weren't clear about how to use them. We had double jump on space pressed twice, wall jump on space pressed while against a wall, the gun on left click, and a dash on right click.
You're totally right about the gun though, it was a last minute effort to get the final power up finished before the deadline and its a bit too high.