Roam the Outer Sunset, then dig anywhere. Spray the gulls, crabs and worse until they pop, or drop rocks on them. Dig up glowing power-ups and collect the junk of history. Dig out whole chambers and they deal with the monsters for you. The deeper you go, the nastier it gets.
Arrows or WASD to dig. Space to spray; hold it to keep pumping. P pauses, M toggles music.