Having most pieces promote makes the game more shogi-like than chess-like, and I would like to avoid that. For this reason I also specified promotion on last rank, rather than in the camp.
If mating potential would be a problem, I'd rather adopt the rule that a bare King loses. But I am not sure it would be a problem. Eliminating all Pawns when you are behind is easier said than done. When behind, you will not be in a position to gain them. So you would have to sacrifice them away, where each Pawn would cost you yet another piece. For the Rams that is fine, as these are practictically useless on a near-empty board, if not from the very beginning. But there are many more Pawns than Rams, and you would have to eliminate the Warriors too.
I have little doubt that 3 minors could checkmate a bare King, even on 18x18.
Having most pieces promote makes the game more shogi-like than chess-like, and I would like to avoid that. For this reason I also specified promotion on last rank, rather than in the camp.
If mating potential would be a problem, I'd rather adopt the rule that a bare King loses. But I am not sure it would be a problem. Eliminating all Pawns when you are behind is easier said than done. When behind, you will not be in a position to gain them. So you would have to sacrifice them away, where each Pawn would cost you yet another piece. For the Rams that is fine, as these are practictically useless on a near-empty board, if not from the very beginning. But there are many more Pawns than Rams, and you would have to eliminate the Warriors too.
I have little doubt that 3 minors could checkmate a bare King, even on 18x18.