Twix

Twix is an implementation of the board moving puzzle known as Khun Phaen Escapes, usually manufactured with wood pieces. On a 4x5 board there are ten stones. Four small 1x1 pieces, four 1x2 pieces, one 2x1 piece and a single 2x2 piece. The goal is to bring the large square to the opposite side, which seems to be impossible first, as there are only two free fields to move and rearrange the pieces. Indeed this puzzle is not trivial, the common solution takes 103 steps, the currently best known strategy 79 steps.

In the game Twix you have to move the stone from the left to the right by selecting the piece to move and then move it with the cursor keys. The implementation is quite special, as the game code itself is not executed as an Atari ST program, but as a program for the Hewlett Packard 48SX pocket calculator which is then emulated inside the ST game. This is visualized by a 48SX on the screen and all the action is only taking place in the small monochrome display of this picture.