Slimetrail is a two-player, abstract game played on a rectangular grid (or a rhombus made of hexagons, as in Hex). Each player takes turns moving a piece around the board. The piece can be moved one space, and may not re-visit a visited cell. Two goal cells are located at diagonally opposite corners of the rectangle (or in the obtuse corners of the rhombus). You win if either player moves the piece into your goal cell.
The rules at Game Cabinet state that "the piece starts on any mutually agreed upon square". But since this is a finite game, with enough computing power it can be determined which player has the winning strategy depending on the initial placement, so in principle no cell would be mutually agreeable. In practice, the Pie Rule can be used.