- Moving stage: Click a tile to make it green. Click an empty square in a clear straight line to move that green tile; it then becomes red and cannot move again this turn. Move up to 6 tiles this way, one at a time.
- When done moving press REMOVE WORD button to enter removal stage.
- Removal stage: Click a valid word of 3–6 tiles (they turn yellow) in a contiguous straight line, then press REMOVE WORD again to remove it. All moved (red) tiles must be part of the selected word -- you cannot simply move them out of the way.
- Bomb: Once per game, you may remove the then-active (green) letter using the Bomb button. This can make room for longer words, or can help clear the board.
- End Game: To end the game for any reason, including inability to make any move at the end of a grid, click END GAME, which upon confirmation will bring up the score screen.
- Scoring: Removed words score the square of their length (9/16/25/36), plus bonuses for rarer letters. Clearing the board scores a 25-point bonus. An unused Bomb scores a 5-point bonus at game end. Big Square was developed by Quickthorn Games, which is Brian Kravitz, David Kwong, and Dave Shukan.