Swarm.

Drag anywhere to steer. Your squad shoots on its own. Arrow keys or A / D work too.

Shoot the gates. Every few hits adds a recruit. Turn red gates green, then walk through one.

Break weapon crates. Move into the floating gun to equip it. More soldiers means more firepower.

Dodge what you can't destroy. Enemies and boss shots cost soldiers. Kill the boss before it reaches your squad.