This will probably run better with Phosphorus, given you aren't using Chrome OS. Use arrow keys to move around. Press S to fire. Press UP or A to jump. Press P to toggle the controller in the bottom-right corner. Press Q to reset your position. This can only be done if you are touching the edge. Press Z to switch between the blaster, cannon, and machine gun. The blaster deals less damage, but has more fire rate. The cannon deals more damage, but you must wait 3 seconds between shots. You can spam the machine gun, but be aware you have less speed while firing. Press W to change the stage. Every time your difficulty increases, you will obtain extra max health. The difficulty can easily ramp up, too, so that extra health will be a big help! You can obtain the shattered soul after defeating the Doom Vortex. Using it by pressing B will summon the Mirror Ghost. You can also obtain the nuke after defeating the Ultra Drone. The nuke can be a big help with the floods of drones that appear. Obtaining it destroys all the drones.
I made it all myself. I was looking at my past projects and I looked at my Laser Tag Test Zone. Then I looked at my NES animation. And then I looked at my "Testing..." project. Then I thought: "This could be a big thing!" And thus was how this was created. Bosses: Difficulty 10: Ultra Drone - Fires lasers at you if it gets close. Try hanging off platforms and moving backwards to take it down. Difficulty 25: Doom Vortex - Summons Vortex Drones to try to destroy you. Get too close and it will suck you in, dealing damage, before launching you back out. Shattered Soul: Mirror Ghost - Flies around, trying to shoot you. Move. Avoid his shots.