The problem with WWI as it is is if there's 1 player they're either a WWI ace or they suck. Either way it's no fun.
2-3 players mean an ace or two plus an average Joe. The aces are usually on the same side flying Dr-1's. Do you go die with average Joe or gang against him? There are no good options.
4 or more becomes interesting with 10 being seemingly ideal. 4 can still suck because of some of the above but at 10 there's enough chaos to break down some of the natural groupings.
I'll go there any time I see 5 or more players but that's rare.
