Classic minesweeper, except some of the numbers are lying by one. Work out which.
Numbers count the mines next to them. Some numbers lie by exactly one. Dig to open a cell, Flag to mark a mine (right-click works too), Accuse to call out a lying number. A correct accusation shows the truth for free. A wrong one costs an accusation. Hit a mine and it is over. Keys: D, F, A.