maybe i'm insane and/or blind, but is there a reason for the different figure colours? or the white border around figures in the book?  we don't follow the colour in the book for laziness sake. 

"Important: After the marine players have chosen
which color figure they will use in the game,
return all unused marine figures and all the
invader figures of those colors to the box. Any figures
returned to the box may not be used in the
game." (p. 4)

Puts a limit on the number of invaders that can be out there at any given time. White invaders are always spawned, regardless of the Marines present, Blue/Green/Red invaders are Marine dependent.

 so yes, i AM blind... lol.  or could be the fact that my rulebook is a LOT more faded than my beserk tokens are supposed to be. *laugh*

thank you

It was an attempt at balance and scale. If you only have the Red marine, you can only put in Red invaders, and there's a physical limit to the number of invaders that could be present. If you have 3 marines playing though, you can use all the figures (well, all if you're not using the expansion, if you  are, then you need to swap out 1-for-1 the figure type).

-shnar

its a great way to balance the game