Ah, Champions. I spent MANY hours playing this gem. I'm not sure what iteration they're up to now, but my last experience was with third edition.
Champions, also known as the Hero system, is a point based generation system with an effect based array of powers. One does not purchase a fire blast. One purchases and energy blast and describes it as fire. The system is a bit math heavy for my taste, and back in third edition very vulnerable to min-maxing. Someone with number crunching skills could easily destroy someone with a more concept based approach to character design. Most of the actual crunching takes place during character creation, though, so once the character was ready to go, game play was fairly smooth. Having large numbers of six sided dice is handy, as players will frequently be rolling 8-12 dice for effects at playable power levels. The system is flexible enough to allow for any character concept I could dream up, and I don't remember seeing anyone on the comics I couldn't reliably reproduce.
For that reason, I think Champions could work as a play by post on a platform that rolled dice for you. Character creation would be time consuming, but then, when isn't it? But the lack of on-the -fly calculation makes the game quite workable.