Herd by day. Hold the line by night. Raise a flock on a strange frontier with a pack of dogs with back mounted turrets and defend it from what comes for them after dark.
One laser. Build a machine of mirrors, splitters and lenses that burns every step of the path. Light gets tired: every enemy it passes through drains it, so where you split and where you strike is the whole game. A tower defense where you engineer the damage. When it slips mid-wave, grab a mirror.