Swap neighbours to line up 3 or more. Every match earns a tilt: pick any wall and the whole pile slumps toward it. If the slump makes a match, that tilt was free, so keep tilting and the chain keeps growing.
After every swap a wave of gems pours in from the far wall. If the board fills up, the game is over.
Tap two gems or drag one to swap. Tap a wall, or swipe across empty space, to tilt.
The pile stays exactly where it slumped.