[[quoteright:250:http://static.tvtropes.org/pmwiki/pub/images/Gamma_World_cover_3287.jpg]]
[[caption-width-right:250:Not pictured: gun-wielding mutant bunnies.]]

A classic role-playing game originally created by TSR, the same people who made ''TabletopGame/DungeonsAndDragons''. Centuries after a vaguely defined apocalypse, a radioactive and ruin-strewn Earth is inhabited by mutants, sentient animals and plants, and insane half-functioning robots, all of whom compete for influence as multi-species civilization begins its long climb to recovery. ''Gamma World'' was heavily influenced by TSR's earlier sci-fi RPG, ''Metamorphosis Alpha''.

Despite what a newcomer might think, the tone is quite light-hearted, and the players are strongly encouraged to have fun and not think too hard about how silly it all is.

The game has gone through seven editions so far; TSR published the first three from 1978 to 1985 with their own unique rule sets. 1992's 4th Edition was based on the same engine as ''D&D'''s 2nd edition, and 1995's 5th was a supplement for the sci-fi RPG ''TabletopGame/{{Alternity}}''. In 2002, WizardsOfTheCoast, which had since absorbed TSR, published a wacky homage to ''Gamma World'' entitled ''Omega World'' in ''Polyhedron'' magazine.

The setting was licensed by Sword & Sorcery Studios (a subsidiary of Creator/WhiteWolf) and heavily revised for ''TabletopGame/D20Modern'' in 2003. This new edition recasts the apocalypse as a war among post-[[TheSingularity Singularity]] civilizations, a horrific spasm of nanotechnological and biological warfare (with a few nukes thrown in for old time's sake). The old creatures and robots are nearly all retained, but given new and detailed explanations that are designed to elicit horror and awe rather than cheap jokes.

Most recently, WizardsOfTheCoast released a seventh edition of ''Gamma World'', using the 4th edition ''TabletopGame/DungeonsAndDragons'' rules, in October 2010. The game was far more humorous, from character creation to Omega Tech descriptions. The 7th Edition setting is one where "the Big Mistake" merged all possible worlds into one, and really leaves the door open for player interpretation.

That edition fell victim to the most notable trend in ''Gamma World's'' long history: usually, only a handful of books are released before a new edition comes out and renders all the previous books obsolete. This reached its zenith with the ''TabletopGame/{{Alternity}}'' version, which had only a single, core rulebook released before being discontinued.

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!!This game includes examples of:

* AdamAndOrEve
* AdaptationDistillation: ''[[TabletopGame/D20Modern Omega World]]'', a tribute to the original game.
* AdventureTowns: The breakdown of communication and other infrastructure leaves most of the world in its own little corners. Villages, bunkers and city-states may exist at widely varying tech levels, and cultural norms vary wildly.
* AfterTheEnd: While it's generally played for laughs, it's BlackComedy at best.
* AmazingTechnicolorPopulation: Antimatter Blasters are blue, Demons are red, and Photonics come in shiny red, blue, or green.
* AmmunitionBackpack: Contained an atomic energy cell that powered the fusion rifle.
* AncientConspiracy: Several editions include theories that the apocalyptic event and some of its consequences were the results of conspiracies beforehand.
* ApocalypseHow: Class 2
* ArtisticLicensePhysics: The game is meant to emulate pulp post-apocalypse, and nobody should mistake it for any kind of science text.
* AttackItsWeakPoint: Adventure [=GW1=] ''Legion of Gold''. An amoeboid monster' body can withstand 1,000 HitPoints of damage, but its nucleus can only take 50 HitPoints before it's killed.
* AttackReflector
** The Reflection mutation causes damage inflicted by an opponent to rebound on that opponent. The fraction of damage reflected decreases during use. The first turn the mutation is used all damage is sent back at the attacker. The second turn only half the damage is reflected, and in the third and subsequent turns only one quarter of damage is returned to the source.
** The Life Leech mutation allows a mutant to drain HitPoints from all creatures within range. If a creature within range has the Anti-Life Leech mutation, the mutant using Life Leech loses HitPoints and the mutant with Anti-Life Leech heals that number of HitPoints.
** If a creature has both the Absorption and Energy Metamorphosis mutations, it can absorb incoming attacks and use them to heal HitPoints of damage. If there's an excess of energy the attack is redirected back at the source of the attack, damaging it.
* AtomicSuperpowers: Earlier editions leaned heavily on radiation as the source of the bizarre ecosystem. More recently, see GeneticEngineeringIsTheNewNuke.
* AutoDoc: The 1st Edition Medi-Kit.
* BeastMan: In a wide variety, including one-of-a-kinds.
** BigCreepyCrawlies: Cockroaches and Arachnoids.
** BigfootSasquatchAndYeti: Yetis.
** EverythingsBetterWithMonkeys: Simians.
** EverythingsSquishierWithCephalopods: Octopoids.
** LizardFolk: Saurians.
** WingedHumanoid: Hawkoids
* BlackComedy: The entire landscape is a mass grave, but it's hard to feel terribly somber in a world where location names are puns, monsters have LegoGenetics and alphabet-soup names, and your heroes look like the rejects from any ''other'' game's monster lists.
* BrainInAJar: Borgs, Permanent Cybernetic Installations and Think Tanks in 1st Edition.
* ChameleonCamouflage: The Chameleon Powers mutation in the 1E game.
* CityInABottle
* CollectibleCardGame: 7th edition had its powers and technology sold on this model; [=GMs=] and players had to buy more cards in booster packs for more fantastic stuff to use in their RPG, instead of buying them in sourcebooks. [[InternetBackdraft This marketing concept was not well received.]] However, the core game ''did'' include include a full deck of mutations and Omega Tech (Loot), so players weren't required to buy boosters.
* CrapsackWorld: Terrible things have happened to this world, and the few survivors who aren't living hand to mouth seem intent on raiding or oppressing their neighbors. There seems little or no prospect of Gamma Earth climbing out of its dark age any time soon.
* CrystalDragonJesus: Some of the 'new' faiths seem strangely familiar.
* DarkerAndEdgier...
** The 6th Edition for ''TabletopGame/D20Modern''.
** The original game when it first came out. It's said to have popularized dark humor in [=RPG=]s.
* DashAttack: In the adventure [=GW6=] ''Alpha Factor'', the mutant creatures known as the S're'daan and the Ba'crolbai would [[HornAttack attack opponents with their horns]] after charging into them.
* DuctTapeForEverything: We're sure you'll find a use for this...
* FantasticRacism: The Knights of Genetic Purity, the Iron Society, the Zoopremacists...the list goes on.
* FungusHumongous: Adventure [=GW1=] ''Legion of Gold''. The buggem lair has a room filled with a fungus garden made up of tall, shrub-like fungi.
* FunnyAnimal: 'Mutant animals' played by characters tend to fall into this category - certainly that's what most of the art depicts. Other mutated creatures in the setting have a much wider range.
* GeneticEngineeringIsTheNewNuke: Nanotechnology and its use in altering genetic code have become dominant over the old power source, [[ILoveNuclearPower 'The Bomb did it.']]
* HomeFieldAdvantage: The adventure ''[=GW6=] Alpha Factor''. Jeremiah Coot has filled his base Mindkeep with all sorts of traps, including false vines that cause any opponent who tries to swing on them to fall.
* HornAttack: Mutant characters could have horns as a mutation. The mutants known as Rakoxen (and Hoppers in 2nd Edition) had them. Two new monsters in the adventure [=GW6=] ''Alpha Factor'', the S're'daan and the Ba'crolbai, had horns that they could use to attack opponents after [[DashAttack charging into them]].
* HorseOfADifferentColor: Mutant horses, giant horses, podogs, ''cactus horses''...
** ...and jackalopes. (Seriously.)
* ILoveNuclearPower: Depending on the editions and your character's stats, a refreshing radiation bath may grant you superpowers.
* ImprobableWeaponUser: Since the game is set in a ScavengerWorld, it is almost a given that your characters will be these. You could wield a stop sign, a telephone pole, vending machines...really anything you can think of that fits within the one-handed/two-handed light/heavy melee/ranged parameters.
* InTheFutureWeStillHaveRoombas: In 1st Edition (1978), the General Household Robotoid is designed to clean homes. It has tools such as cleaners, polishers, disinfectants and vacuums.
* KillerRobot: Technically could be your player character. The Created are an entire faction made of Killer Robots.
* LightEmUp: Photonic origins.
* LostTechnology: Most campaigns will feature efforts to recover forgotten technologies at some point, and most characters will carry and employ devices they do not really understand.
* MachineWorship: Present in some areas.
* MakeMeWannaShout: The 1E Sonic Attack Ability mutation.
* TheMultiverse: The seventh edition backstory features the Large Hadron Collider causing several different realities to intermingle and exchange places, in an event called "the big mistake". Furthermore, Dopplegangers create their doubles by pulling them out of alternate realities.
* {{Mutants}}
* NanoMachines: The concept didn't really exist yet in the earliest editions, but the sixth edition relied heavily on this kind of technology to apply BetterThanABareBulb to some of the ludicrousness.
* NinjaPirateZombieRobot: Because you can choose two origins for your character, and the origins are each quite different, you can end up with lots of these. Android Plants, Vampire Octopoids, an enormous horde of tiny yetis...
* OverclockingAttack: Alpha mutations have this option, with a 45% chance of failure.
* PlantPerson: Mutated Plants are an uncommon option for players. A few other plants in the setting employ a humanoid form, albeit usually only as bait.
* PlayingWithFire
* PsychicBlockDefense
* RadiationImmuneMutants: Notably averted. While there are mutations that allow for resistance to radiation, it isn't universal to all mutants.
* RagnarokProofing: Judging from the gear lists, some surprisingly mundane objects were engineered to survive centuries.
* RapidAging: The mutation Hands of Power has four variants. The fourth one is Withering Hands, which causes any creature touched to immediately age 1-10 years.
* RecycledINSPACE: It's ''D&D'', but [-[[AfterTheEnd AFTER THE END]]-]! [--[[SlidingScaleOfSillinessVersusSeriousness AND SILLY]]--]!
* RuleOfCool: There aren't many efforts at justifying all this strangeness...
* RuleOfFun: ...and why should there be?
* ScavengerWorld: Even the wreckage of the lost ages is much better than the best hand-made products of the new.
* ShoutOut
** Original 1981 rules booklet. The Treasure List at the end of the book has a number of references to other works.
*** A "pleasure globe" that gives the holder pleasurable sensations. The 1973 movie ''Film/{{Sleeper}}'' has such a device in use by a future U.S. society.
*** A "Mama" doll. Near the end of the original 1968 ''Film/PlanetOfTheApes1968'' movie, a doll that says "Mama" appears as evidence that humans could once speak.
*** A "Rollerball" trophy (from the original 1975 movie ''Film/{{Rollerball}}'').
*** A tuba that was mashed flat by a steamroller. In the 1978 ''Series/{{MASH}}'' episode "The Smell of Music" Major Winchester's French Horn is crushed flat by a steamroller.
** Module ''Famine in Far-Go''. The {{PC}}s can find an ID card with a {{Hologram}} of a bearded man and the inscription "Executive Pass, E.G.G., Pres." This is a reference to E. Gary Gygax, then President of the company TSR that created the ''TabletopGame/GammaWorld'' game.
** 1983 edition boxed set "Adventure Booklet". One of the buildings in the destroyed city of Pitz Burke (Pittsburg) is Rossum's Universal Robots A&W Division. It once belonged to the RUR Corporation, which made almost 40% of the robots in the world before the Social Wars and the end of civilization. This is a reference to Rossum's Universal Robots in Karl Capek's play ''Theatre/{{RUR}}'', which also manufactured robots.
** 1986 module [=GW6=] ''Alpha Factor''
*** Rakees are mutated flying squirrels who can't be killed. They're taken from Rocky the Flying Squirrel, who appeared in the ''WesternAnimation/RockyAndBullwinkle'' show.
*** Bokshee is a man who guides the {{PC}}s across the AfterTheEnd landscape of ''TabletopGame/GammaWorld''. This is a reference to Creator/RalphBakshi, who led moviegoers through a similar mutant-filled post-apocalyptic world in his film ''WesternAnimation/{{Wizards}}''.
* ShroudedInMyth: The world before the Cataclysm. Old technology are known as artifacts, electricity is called lightning and machinery, particularly robots, are called live metal.
* SicklyGreenGlow: Radiation tends to give off this helpful warning glow, which has saved many, many lives.
* SlidingScaleOfSillinessVersusSeriousness
** The original game, 4th edition, and ''Omega World'' are so far on the silly scale that it mutates and flies out into space. 3rd edition and 6th edition, while not exactly ''serious,'' make an effort to portray a world that's a little more plausible.
** 7th Edition is much closer to the silly end, including a suggestion that you could respond to a villain by pulling out a cane and singing and dancing like Michigan J. Frog, a backstory in which Peshtigo, Wisconsin suffered nuclear annihilation by the French an untold number of times over (it's said to have happened in 3% of the originally-separate universes that combined into Gamma Terra), random shout-outs to virtually everything under the sun, and not even an attempt to make the yexil (Basically cloth-eating anthropomorphic manticore bandits with laser eyes--no, really) or the other more bizarre monsters anything except completely ridiculous.
* SlidingScaleOfTurnRealism: Round by Round.
* SpareBodyParts: A not-uncommon result of mutation. This is possibly the only game system in which your total count of limbs may ''increase'' over the course of the campaign.
* SpikeShooter: The mutations "Quills or Spines" and "Thorn Thrower" allow creatures to throw quills, spines or thorns at opponents and damage them.
* SupernaturalFearInducer: The mutation Fear Generation instills complete terror in a creature, causing it to run away for an entire minute. If the target can't run away it will collapse into unconsciousness.
* SuperPoweredRobotMeterMaids: Literally.
* SuperSpit: Several ''Magazine/{{Dragon}}'' magazine articles gave new mutations and mutants with this ability, and the Bu'daan in [=GW6=] ''Alpha Factor''.
* SwissArmyWeapon: The Chameleon Rifle in module [=GW6=] ''Alpha Factor'' can be configured in several different ways.
* {{Telepathy}}: Having the Telepathy mutation allows a creature to read the emotions and thoughts of other creatures and send its own thoughts to them.
* UniversalAmmunition: The 7th edition uses an abstract system of ammunition, where any weapon can use any type of ammo. However, using more than one shot per encounter will cause you to run out.
* UnspecifiedApocalypse: Most of the game's versions are highly vague about the reason why Earth has been destroyed.
* VampiricDraining: Adventure [=GW1=] ''Legion of Gold''. In the buggem lair, the parn embryots will jump onto victims' heads or shoulders, bite them and suck out their bodily fluids at a rate of 10 HitPoints per combat round
* WeakenedByTheLight: While in bright light, a mutant with the Dark Dependency mutational defect is nearly blinded and takes 1-8 HitPoints of damage per four hours of exposure.
* WetwareCPU: Androids. Inverted with AIs.
* WhenTreesAttack: Plants are a possible character origin in all of the editions. Also there have always been numerous species of plant-monsters to spice up wilderness adventures.
* TheWormThatWalks: One of the possible character origins. Depending on your primary origin and your secondary origin, you could be anything from a horde of cockroaches, to a [[GreyGoo mass of nanomachines]], to a horde of ''[[CuteKitten sentient, hive-minded kittens]]''.
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