Object: Capture your opponent's King.
 
You have to move a piece that is adjacent to another of your pieces. Only if this is not possible you may execute any other legal chess move.
The king may walk into and through check. You have to capture your opponent's king to win the game.
Apart from this, the standard chess rules apply.
 
Companion Chess has 15 variants. In the other variants the supporting adjacent piece must be North, South, East, West etc. Note that for White North is up, but for Black North is down; similar for the other directions.
 
 
More freeware as well as real puzzles and games at my home page: http://karl.kiwi.gen.nz/.