The Base system is D20 Modern with the D20 Darwin's world (third party Suppliment). D20 Past is an additional resource however Some options in this may not be available (epic/prestige classes) and will require certain backstory requirements but are possible The campain planned so far is base building, exploration and survival. It will be fairly grim and dark and will have elements of Gritty realism. The only "Races" are Human, Mutant and possibly android/Robot although these races will be at a disadvantage (need to be repaired and can't be healed). The main theme/setting is Nuclear Apocalypse and is set in the real world. It will be based roughly 100 years in the future after the apocalypse. Other Apocalypse types may be added as additional campaign difficulties but that will be decided in the Session 0 (Ai/robots, Zombies, Aliens, fantasy elements (demons/devils, magic etc) may be included to some degree) It may be possible to include fantastic races (elves, dwarves, orcs, etc) although these will only be flavoring/re-skins and WILL NOT have any stat modifiers (for potential future PC's). The same is true for any magic encountered, it is not something that will be readily available to the party if at all as it will take away from the survival elements. It is possible that it could be something the players come up against.