Plain Mutazone requires moving a survivor to dodge endless waves of zombies and mutants. i use automatic shooting to handle attacks while focusing on movement.
Step requires moving your survivor, automatic shooting fires without clicking, you must dodge attacks and reposition constantly.
Controls are not stated, only movement and automatic shooting are mentioned. Features are not stated, no timer, hints, toggles, modes, or levels are described.
Most quick thinking helps to master the game. Stick close to edges to keep enemies in sight. Use boosts for dense waves if stated, but only stated mechanics are movement and shooting.