I'm using my old review format from the Amber Zone reviews to discuss this game book.
C-Atom is a compact (less than 50 pages of rules!, and that's digest-sized pages) rules-light game set on Earth, after a cataclysmic war that ended the world. Nuclear weapons, poison gas, germ bombs, you name it. All the nasty stuff you can think of has happened. C-Atom is not set up for complex characterizations, and nuanced interactions with exactingly detailed NPC societies. It's a 1950's vintage Atomic Horror movie. The author calls it a “beer and pretzels” game.
Location: The game's setting implies that the whole Earth was affected by the Final War. So the PCs can begin play in their own home town if they want, or pick any place on the planet. It's terrible most everywhere, though, so expect trouble wherever you begin.
Mission: Survive! Maybe the PCs can find someplace that isn't ruined by Contamination where they can find a bit of peace and begin to rebuild the world. The rebuilding part, however, is outside the scope of the game.
Complications: There are mutants and monsters and out-of-control robots aplenty to ruin the PC's day. Even the environment is out to get you; Contamination is everywhere, and will Mutate you with enough exposure. Most of your equipment must be scrounged. Fortunately there are some high-tech goodies to be found - like Jetpacks!
Strong Points: C-Atom gets a lot done in not a lot of space. PCs and NPCs are super-fast to create, and with a familiar setting (Earth) play can get started right away. The game's objectives and story-focus is not limited – it's precise. It is trying to do just one thing, and that it does nicely. Imaginative players can throw in whatever sub-plots they may want, or concentrate on blasting that next Lobstrosity or Spidergoat before their ammo runs out.
Weak Points: Okay, a quibble. Mutations are referred to in one place as Flaws and Perks, but not in the tables that explicate what the mutations actually do. It should be consistent.
What I'd change: This setting is not my cup of coffee, but like every other RPG product I get my hands on, I pored over it looking for things I can use in Traveller (and now also Cepheus Light & Sword of Cepheus). So not to change, but to <ahem> borrow: the Mutations fit in well with my concept of Genetically Modified Humans. C-Atom presents Mutations both beneficial and baneful, and I'll use both. The Contamination idea in general is usable as a different environmental hazard to encounter. The Unusual Weather table is handy – throw a quick complication at the PCs while they're out exploring.
In My Traveller Universe: Mutations, radiation and nasty WMD's could appear anywhere in my TU.
To Sum Up: A mechanically-simple game that your game group might try for a change of pace. It is simple enough in concept and execution to spring on a party or family get together for an impromptu game that will surely bring lots of laughs. Not a game for the serious role-player, or for those who don't want to suddenly develop Laser Eyes.
Omer was kind enough to send me a complimentary copy of Cepheus Atom.