The first diagram here shows an infinite board with a corner on a1. I believe that White can force mate when he has King (d4) and Rook (h8) against a lone Black King (f6). White needs to get his two pieces together, somewhere like Rook (p16) and King (p14). Then the slow process of pushing the Black King down to (a1) can begin.
Infinite Chess is actually played on a finite 'figure-eight'board.
Keith Douglas posted Chess with an Infinite Board in 1997.
The first diagram here shows an infinite board with a corner on a1. I believe that White can force mate when he has King (d4) and Rook (h8) against a lone Black King (f6). White needs to get his two pieces together, somewhere like Rook (p16) and King (p14). Then the slow process of pushing the Black King down to (a1) can begin.