by morningstar
Personally, I don't think it's any more or less fun with any different numbers of players. The difficulty may be slightly different, but that can be adjusted to your liking.Actually you can come up with some crazier schemes with larger groups of players, but I never felt like that was a requirement to have a good time with the game.
In any case, being a cooperative game, you could easily play two hands each with the four player rules.