A top out occurs when:
- a tetromino cannot be place at least partially within the play zone.
- garbage pieces are sent, pushing the top pieces above the spawn zone.
Top outs usually result in a game over, however some games such as Tetris Blitz will instead allow the player to continue playing after clearing part or all of the field.
There are several variations of what constitutes a top out:
- Block out: a piece is spawned overlapping at least one block in the playfield
- Lock out: a piece locks when it is entirely out of bounds (that is, in the vanish zone above the ceiling)
- Partial lock out: a piece locks when it is partially out of bounds, even if it would clear a line
- Garbage out: After lines are cleared and garbage is added, a block remains out of bounds.
- "Top out": A variant of garbage out used by Guideline games where the block must be pushed above the vanish zone.
Different games have used different combinations of these conditions:
- This list is incomplete.
- Tetris (NES, Nintendo): a piece locks overlapping at least one block, but in some cases it is possible to move or rotate out of such a situation.
- Tetris (Game Boy): Two consecutive pieces lock in their spawn positions.
- Dr. Mario, Tetris and Dr. Mario, Super Puzzle Fighter II, Kirby's Star Stacker: block out
- Bombliss: garbage out
- Tetris (Atari), Tetris (NES, Tengen), The New Tetris, and Tetris DS (push mode): partial lock out or garbage out
- Tetris 2 + Bombliss: block out or partial lock out
- Tetris DS (standard mode and mission mode) and most other recent games: block out, lock out, or "top out" garbage out
- Puyo Puyo: the top visible cell of the column left of centre is blocked on spawn (in Fever rules, either centre column may be blocked)
- Tetris Attack: garbage out; in multiplayer mode, evaluation is delayed by a split second