An endless board you can pan in any direction.
How to play
Normal chess armies, but the board never ends: pieces may walk, leap and slide past the old edges in any direction. Drag the board (or use the arrows / keyboard) to pan; Center jumps to your king. Sliding pieces travel at most 4 squares beyond the outermost piece. Pawns still march toward the old far rank (rank 8 for White, rank 1 for Black) and promote there to a queen, and may double-step on their first move. Win by checkmate; if 200 moves pass without one, whoever has more material wins.