Based on the original Playstation game Intelligent Cube. It has similar rules with a few twists. The in game rules menu explains the rules and controls if you want to try it. Maybe there are others who also have nostalgia for this game!
For best performance you should have gpu acceleration enabled in your browser. I get the best frames per second with Chrome. It's pretty smooth unless there are a lot of other tasks running. I have included a performance mode and a toggle for fps display in the controls menu. It may struggle on slower systems.