I've just updated the game. The fact that it says to use W is an oversight due to the fact that I use azerty (french keyboard) which places W where the Z is in qwerty. The game is much easier to play with C, X and Z lol. But to be fair, the game is better to play with a controller rather than keyboard and mouse.
As for the other feedback, thank you so much for your positive review! I hope you also enjoyed the boss and jetpack area depsite the bad control scheme. You can also change your controls in the options. Thank you !