Really nice game! Even though very first thing I did was walked past Arcade and fell off the edge of world :D Also fell off in the gun stage the same way xD
Introduction of gun seems a bit off. Jumping is done only with Z so using WASD feels unconfortable so I used my second hand to move using arrows. But I also need my other hand for shooting with the mouse! I'd sugest add jumping to space bar - easier to use with both WASD and Arrow keys.