[Gandalf Parker]

Ahhh venomous correctness.

It would be difficult to create a commanders-only game.
Altho there is an interesting side-effect that the OP might not be aware of. That the game is willing to consider any unit to be a commander.

Possibly, look at the All_Units.map which displays every unit in the game, as a commander. Its purpose was to make it easier to look thru everything in the game even if you dont know where it comes from.

Maybe it would be possible to kill off all recruiting then. Can you come up with a plan for creating a game that pre-assigns commanders to each side?

That brings two possible game formats to mind. A chessboard version with each side having matching pieces of specialized abilities. Or (more my style) a game where each gets a random collection to have to work with.