Keep Cells Open
Level: Intermediate
Leave open space to preserve your options.
Empty cells are options. The more open cells you have, the safer the spots new tiles spawn in, and the more freedom you have to slide in the direction you want. With no empty cells, you're forced into bad moves.
Don't let small tiles (2s and 4s) pile up and fill the board — merge them promptly to reopen cells. It's especially important to clear out stray values that aren't part of your chain quickly.
Dropping to two or three empty cells is a warning sign. At that point, prioritize merges that open up space over ones that just boost your score, and get the board breathing again.
Related Strategies
Endgame Management
Once the board fills up late-game, managing empty cells becomes priority one.
IntermediateSetting Up Chain Merges
Line up values so multiple merges fire in a single move.