Tactex is a hexagonal version of TacTix, a two-player strategy game invented by Piet Hein. In TacTix, players alternate taking pieces away from a square (or rectangular) grid, as many contiguous pieces as desired from a single row or column. The player who takes the last piece loses (misère play). In Tactex, pieces are placed on a five by five by five hexagonally-tiled field and are removed from one of the nine vertical columns or eighteen diagonal rows. The objective is the same.

Here's the starting position.

Here's a possible second move.

And a third

And a fourth