Objective

A garden hose has cut a rill through a backyard sandbox and your clay marble is riding it. Steer left or right — drag anywhere, or use the arrow keys — and the marble takes on 4.6 units a second of sideways speed. The water adds its own on top.

The current

The rill runs in bands 18 units long, and each band shoves one way, the other way, or not at all. The foam inside a band leans the way it pushes, so you can read the next one long before you reach it. A band starts at 1.0 units a second and grows to 2.0, so full steer against the strongest water still crosses the rill at 2.6.

Scoring

One point for every shovel row you clear, three for every teal shell. Gaps start 2.6 units wide and close to 1.6, and rows arrive 1.77 seconds apart at first and 0.76 apart by 28 seconds. Only the shovels end a run — the banks just pen you in, and the water will happily hold you against one.