I was assuming that the "main player" was equivalent with the "active player"; that is, you are only considered the "main player" when it is actually your turn. As such, some of the alien powers would only work when you are on offense (you are the active player) and not defense. As such, there is only ever one "main player."

However, one of the variants (I forget which), references "main players", suggesting there can be more than one main player at once. Is it possible we made a mistake and a main player is anyone involved in combat that is not an ally? That is, both the offensive player and defensive player are "main players."

Any help to clarify this is appreciated, as so many of the alien powers only work when you are the "main player."

Page 8 of the rules, lower left corner, indicates that the term "main players" means the offense (the player whose turn it is) and the defense (the player whose color was selected by Destiny). In any given encounter, you're either a main player, an ally, or not involved.

Thanks for the quick response! I admit as I searched the rules this slipped by me. I will need to highlight the ref in the rulebook (thanks for pointing me in the right direction). Unfortunately, I interepreted it incorrectly for our first few games. Not again....