A top out occurs when:
- a tetromino cannot be placed 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, in Tetris Blitz, top outs result in a 5-second penalty.
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. This is not used in the Tetris Guideline as of 2009.
- Garbage out: After lines are cleared and garbage is added, a block remains out of bounds.
- Line 41+ garbage out is the version used in the Tetris Guideline.
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): Similar to NES Tetris, but slightly more lenient in ways that aren't fully understood
- Dr. Mario, Tetris and Dr. Mario, Puyo Pop, 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 Attack: garbage out; in multiplayer mode, evaluation is delayed by a split second
- Tetris DS (standard mode and mission mode) and most other recent games: block out or lock out