Afghanistan was occupied by the USSR in 1980, but they really didn't control the country at all. Russian troops mainly held the big cities and got bogged down in asymmetric warfare with various guerrilla factions.

In my mind it would be playable, but not as a standard country. Basically a player could control the opposition forces in the country and make appeals to other countries for help. Anyhow, its sort of moot since I'd much rather play Pakistan.