This ♊ is already dead, he just doesn't know it. Arrow keys/WASD to move. Z/J to jump. X/K to shoot. V/B to switch weapons. Mega Buster: The classic weapon. Shadow Blade: Moves wherever the mouse goes. Air Shooter: Flies upward, acting unbeatable. Gemini Laser: Bounces off walls until hitting its target. Crash Bomb: Attaches itself to a wall, then explodes. Bubble Lead: Mainly sticks to the ground, but can go through the air or walls. This might not be my best work...
Credit to Capcom, the Sound's Resource, and KHInsider!