The player is presented with a blank board, and a list of numbers for each row and column. These numbers represent how runs are organized within any given row or column. For example, a number sequence of “4 8 3” would mean there are sets of four, eight, and three filled cells, in that order, with at least one blank cell between successive groups. The objective of the game is to use these hints to uncover the actual solution, and do this as quickly as possible.
A left-click (un)marks a cell as occupied, while a right click (un)marks a cell as empty. Dragging may be used to mark several cells in a row or column in one go. The elapsed time is displayed in the status bar, and an overview of the game board is located in the upper left corner. A game is completed once all occupied cells have been marked correctly.
The current placement of boxes and crosses (referred to as 'states' from now on) can be saved at any time. Saving a new state does not overwrite previous saved states. Restoring a state always returns to the most recently saved state. This can be repeated until no more saved states remain. The number of actions since the latest saved state is displayed in the status bar.
Picmi includes two game modes. Random puzzles (generated by selecting New from the menu) are generated according to the selected difficulty settings. Alternatively, the included preset puzzles can be played by selecting Load.