Mahjong Dimensions: 350 seconds

The pairing rule from mahjong solitaire gets a twist here — tiles sit on the faces of a rotating 3D cube instead of a flat stack, so you have to spin the shape around to see which pairs are actually exposed on an edge. All of that happens against a 350-second clock, which is tighter than it sounds once you factor in time spent rotating to hunt for matches rather than simply scanning a flat board. Run out of time and you just restart, no penalty beyond starting the level over. The 3D layout adds something flat mahjong doesn't have, since a tile can be hidden by geometry rather than by other tiles stacked on top of it, and the visible board keeps shifting as you turn the cube.