A spray of light streams out of an emitter and across space. Somewhere on the board is a black hole. Your job is to bend the light into it, using nothing but gravity: drop moons, planets, gas giants and neutron stars in its path and watch the beams curve around them.
Drag a piece out of the tray under the board and drop it anywhere. Light passing near it bends towards it straight away, so you can see what each move does as you make it. Press a piece on the board to pick it up and move it again, or drop it back on the tray to take it off.
The meter over the board shows how much of the light is going into the hole, and where the rest went: into a body, or past the hole. Each level has a goal. Hold the meter at the goal for a few seconds and the level is solved. A banner offers the next level, but the light keeps running, so you can stay and push your score higher.
Some levels have a prism, which splits white light into red, green and blue, and holes that only take one colour. Some have a body of their own already on the board that you can't move.
Every level records the best share of light you held while it was solved. The leaderboard ranks how many levels you have solved.