That piece moves as the digital form of that letter or number as given in the ascii table. The stalemate rule is just as in usual chess. Black pieces move just the reverse of the ascii table because they see the board downwards. For example black 4 can move b4,b5,b6,c6,d4,d5,d6 in the starting position. All the other rules can be transferred from the usual chess.
All letters move as their digital forms.
All numbers move as their digital forms. This is an entry in the contest to design a chess variant on a board with 40 squares .