A nearly full board needs a move that preserves another legal action. Before chasing a large merge, inspect whether the resulting tiles can still slide or combine after a new tile appears.
A full board can still have a move
In the original rules, a board is stuck when it has no empty cells and no horizontally or vertically adjacent equal tiles. Diagonal equals do not help. With one empty cell, a successful move can be followed by a new tile filling the available space. Do not assume today's opening will remain open.
Try the steps
- Find equal adjacent tiles and at least one legal direction.
- Imagine the board after the move and a new tile occupying an empty cell.
- Prefer a move with more than one useful continuation when possible.
Should I break my corner strategy to survive?
Sometimes. Keeping a large tile anchored is a heuristic, while retaining a legal move is necessary. Make the smallest useful disruption and rebuild order afterward; no move guarantees a favorable spawn.