by ahmadms
Don't know if you've decided yet, but an 8 player roster will work easily, very easily if no one player misses too many games in a row. We have played this with now about ten or so and it has worked fine, although it is ideal if everyone who's playing gets started relatively early (say in the first five games or so).The winning benefits (extra missiles and starting places) are minor and players who haven't won before get a bonus star for handicap so usually new players (if they get a good grasp of the game rules) are more likely to win.
Yes, if you introduce a new player after having already played a lot of games that might be more difficult, since the complexity of the ruleset will have increased in the meanwhile, so it can be trickier to figure out good strategies. (But then, we did just introduce a new player in our 10th game, so it can be done.) But if you have a regularly rotating roster of players and they're in one game and out the next that should pose no problem at all.