Cubica

Cubica is a spatial fitting puzzle built around cube-shaped pieces that need to be rotated and stacked into specific outlined slots on the board. Each piece only fits correctly from certain angles, so before you can place it you have to work out which rotation lines its faces up with the slot's outline. As more pieces come into play, the board fills up and the remaining open slots get harder to reach without disturbing pieces already placed correctly. It leans on three-dimensional spatial reasoning more than most flat tile-matching puzzles, since you are constantly picturing how a cube will look after a quarter turn before you commit to moving it. Mistakes usually mean backtracking to free up a slot you blocked earlier, which keeps every placement decision meaningful and deliberate rather than automatic.