W - Jump. Holding W lefts you jump higher and fall slower.
A - Move Left.
S - Fall through platforms/ fall faster.
D - Move Right.
Shift - Shoot in the direction you are facing.
Jump on platforms and avoid red spikes and bullets. Shoot flying cannons to destroy them. Move into yellow coins to gain score. Move into the flag for a checkpoint and move into the yellow door to finish the level. I suggest not trying to finish the game, as it goes on infinitely, spawning a never-seen-before level every time the page is loaded.