Themes

Mythology and folklore

• African mythology
• American Folklore (Tall Tales, Historical Legends, etc.)
• Arabian Tales (e.g. Arabian Nights)
• Arthurian legend
• Asian Blend (Chinese, Japanese, maybe Korean, Indian, SE Asian)
• Australian (Aboriginal myth, more recent folklore, and/or the pop myth of Aussie-land)
• Aztec Mythology
• Celtic Mythology
• Chinese Mythology and Folklore
• Egyptian Mythology
• European Fairy Tale Setting (could be more Disney, could be more Brothers Grimm)
• Greek Mythology (or the Romanized version)
• Indian Mythology
• Japanese Mythology
• Norse Myth
• North American Indian Myths
• Traditional English folklore
• Russo-Finnish Mythology (esp. the Kalevala)

Historical and pseudo-historical

• Aerial Warfare (First World War might be ideal)
• Alternative History: we've discussed an alternative Middle Ages, where Egypt ruled the Mediterranean instead of Rome, leaving behind a rather different cultural heritage when it fell
• Ancient Egypt
• Ancient Rome
• Dinosaurs (semi-realistic)
• Gladiator (simple setting, combat intensive, time for the highly detailed and lethal "realistic" combat model)
• Gold Rush!
• Heian-Era Japan
• Medieval Setting
• Organized Crime action, probably in the Prohibition Era USA
• Pirates
• Pre-Columbian North America, with whatever borrowing from native mythologies
• Renaissance
• Solo infiltration mission into a Nazi held castle (I think some game may have used this premise before :-)
• Stone Age (hunter-gatherer)
• Stone Age (primitive agricultural)
• Stone Age (Mesoamerican level)
• Wild West
• Wilderness Survival

Fantasy

• D&Dish stock fantasy world
• Children's Fantasy (Harry Potter, Alice in Wonderland, etc.)
• Conan-style world (mighty swordsmen, relatively rare (but powerful) supernaturalities, very human dominated)
• Dinosaur Sword and Sorcery (with semi-humanoid hero dinos)
• Fantasy, but PC is a monster (dragon, gryphon, demon) who must grow from the weakness of childhood by rampaging across the countryside, terrorizing the peoples, defeating or avoiding the bold knights and cunning wizards and sneaky elves, gathering a hoard of treasure, and establishing oneself as Monster Supreme. See OrcRL.
• Fantasy in modern high school (ala many Japanese/Korean fantasies)
• Fantasy, non-cliche, centered on exploration rather than combat
• Fantasy with small animals as protagonists
• Gothic
• Horror
• Lovecraftian Horror
• Michael Moorcock's Eternal Champion stories (or better, a rip-off)
• Middle-Earth (it's been done; although not mixing it with D&D-generica would be new, problem is, it's hard to do a pure Middle-Earth RL)
• Modern and supernatural (e.g. Buffy the Vampire Slayer, Hellboy)
• Narnian (can take talking animals, human children, and mythological creatures and make a new "Narnian" world)
• Oz (old enough and rich enough to rip off)
• Underwater: fantasy (sea elves, merpeople, no fire elementals)
• Vampire Gothic (modern "gothic")
• Wild West + supernatural
• World without spells
• World without magic items
• Wuxia (Chinese kung fu action fantasy) [calling the martial arts superheros "ninjas" is not a new theme!]

Science fiction

• A universe of giant bug theme races. No humans.
• Alien invasion of Earth
• Earth's invasion of Aliens
• Aliens ripoff: fight alien monsters in underground passages
• Barsoom ripoff (i.e. sword & sorcery in space and with "science" replacing sorcery)
• Comic SF (e.g. Red Dwarf, Hitch Hiker's Guide, Galaxy Quest, Santa Claus Conquers the Martians)
• Cyberpunk
• Cyberspace: The world you are in is a representation of (a) computer network(s). Think William Gibson.
• Fantastic Voyage ripoff (get shrunk and travel the human body)
• Fugitive on an alien planet
• Fusion of Mad Max and Cyberpunk
• Futuristic dystopia
• Gamma World style post-appocalypse
• Huge "generation ship" sci-fi setting
• isolated interstellar colony (no FTL)
• Jack L. Chalker's Well of Souls rip-off, specifically the mix of many "worlds" into a single world, multiple races, technologies, etc.
• Mad Max style post-apocalypse
• Martian colony
• Mecha
• Paranoia RPG's Alpha Complex
• Play a sentient starship
• Robot World
• Salvage mission into alien base/starship
• Space exploration and commercial exploitation
• Space Opera
• Starship Troopers ripoff: fight alien monsters in a very powerful and cool powered battlesuit
• Steampunk
• The AIs have turned on humanity! (or for bonus originality points, the AIs have turned on some alien species!)
• Time Travel
• Tron: You are inside a computer. Each program/command is a species, so plenty of vairety.
• Ultratech Sci-Fi (advanced biotech, nanotechnology)
• Underwater: science fiction (bioengineered or just properly equipped)
• Virtual Reality setting
• High-tech world with almost extinct humans gone savage (Blame!, GUNNM)

Other (the unusual, the crossovers, the hard to classify)

• Alien planet where battle is sex to submission by orgasm
• Anime themes
• Antarctica (penguin based?)
• Atlantis has resurfaced. Explore.
• Cartoon based
• Completely new world "as little related to ours as possible"
• Dimensional crossover (mixing themes)
• Dream world: may be used as a solo idea or in conjunction with another world concept
• Escape from Hell (after arriving via clerical error)
• Furry (any other theme, but races are anthropomorphic animals)
• Highlander (set in present day or progressing through a series of temporal settings) [note: would not be hard to change the premise a little to create a new semi-immortals battle across history background]
• Indiana Jones style archaeological digs
• James Bondesque (or Austin Powersesque) "spy" adventures
• Jungle Adventure
• Lost Valley (PC explorer from modern times, Victorian, 1920's etc.)
• Modern Covert Ops
• Pimp roguelike (and yes, that's pimp in the literal sense)
• Pulp Adventure
• Rescue Worker: could be fantasy or sci-fi setting, but your job is to deal with crisis situations and rescue people, animals, and property
• Shakespearean Roguelike
• Sports (including futuristic or fantasy): try a career as a jockey, a charioteer, a stock car driver,zero-gee soccer/football note: this would be a difficult theme to pull off, IMO, but doable
• Superheroes
• The Quest to Get Laid: Probably modern, seek out and explore strange new sex partners; requires parental warning label (sex could work, romance elements could be used in a roguelike, but can't be central because sex is the mechanics, romance is too intangible for the RL world to adequately handle)
• Underwater: alien (create your own exotic realm of the deep)

Some of these ideas can be combined, others are obviously incompatible.

See Also

List of roguelikes by theme