The primary difference Ahead has from other fungeoids is the structure of its playfield. Called the board, it does not extend infinitely in any direction. Rather, it is bounded at its edges. For example, this program
Il&+1t~j+1*3\~/2<~< >:2)k~tO@~:k\: nl
forms a 20x2 character board, with gaps filled in by space characters.
The IP, or head, does not wrap around when it reaches the edge; instead, it turns around and travels the opposite direction. This makes some program structures in other fungeoids nontrivial in Ahead, but it lends itself to some other unique techniques.
You can also add walls , represented by
#. These cells are like the edges of the board: they cannot be passed through and the head will just turn around when one is in its way.
Aside from these differences, Ahead is otherwise similar to other fungeoids, particularly Befunge and Fish, differing mostly in its instruction set.