I don't understand your question. If YOU are going to make a boardgame, shouldn't
you know how many figures will be included?
If you are talking about the old Lead Edge Board game that used cardboard markers for Marines and Aliens than you would need 20 Aliens, one Queen, two facehuggers, 9 Marines (two with smartguns), one Ripley, Burke, Newt and Bishop. Maybe two dropship pilot/gunners.