Tabletop RPG's are a particular form of Role-playing game.
Participants play characters which consist of different numerical attributes describing their abilities, skills and various other parts of their personality and guide them through a world described by the system's setting and the system's rules, which form the game mechanics. One person is responsible for telling the story, presenting plotlines to the characters and who interacts with them in the roles of various in-game figures called Non-Player Characters (NPCs). He has the final say about all game matters and reacts to the players' actions (or rather to the actions of their characters). Usually, this person is called "Game Master" (GM), but in some RPGs it's Dungeon Master (DM) or Storyteller. Play is completely freeform, i.e. the players describe their characters' actions and roleplay conversations and then the GM decides which effect these actions have on the story, which is often called the Adventure. Think of it as a moderated theatrical play with an open end.
Physical combat and other actions that can't be roleplayed are usually decided with a dice system based on the characters' attributes, although there are some diceless system, too.
Game systems usually consist of a set of rules and a description of the setting, i.e. of the game world and the different peoples. In most RPGs, Player Charcters (PCs) can be of different species (called races by the creators of D&D for some arcane reason, depending on the setting Elfs, Humans, Dwarfs or all sorts of aliens) and of different Character Classes (in fantasy settings these might be Barbarians, Druids, rogues etc. while in Science Fiction settings they might be Space Craft Pilots, Street Samurai or Hackers, etc.).
Apart from commercial systems there are countless homemade systems written by gamers for themselves and their friends.
- Amber Diceless Roleplaying
- Ars Magica
- Chivalry and Sorcerery
- Das Schwarze Auge: A very popular german RPG (translates to "the black eye")
- Dungeons and Dragons
- Dying Earth
- Empire of the Petal Throne: Set in M. A. R. Barker's world of Tekumel.
- The Fantasy Trip
- Hero Wars
- Jorune (also known as "Skyrealms of Jorune")
- Lands of Adventure
- Legend of the Five Rings: Japanese flavoured setting
- Middle-Earth Roleplaying System: Set in the world of J. R. R. Tolkien, based on simplified Rolemaster rules.
- Rolemaster: A rules heavy system with a fanatically loyal but small following
- Tunnels and Trolls
- Warhammer Fantasy Roleplay (WFRP)
Science Fiction settings:
- Blue Planet
- Cyberpunk/Cyberpunk 2020
- Gamma World
- Paranoia: A comedy take on Brave New World and other dystopian science fiction futures
- Star Frontiers
- Star Wars: The famous film has received two RPG treatments, the West End Games (WEG) version covers the original trilogy while the more recent Wizards of the Coast version (based on the d20 system) has been expanded to cover "Episode One" as well.
- Star Trek
- Tales from the Floating Vagabond
- Teenagers From Outer Space: Original anime based game, players take on the role of high-school characters who are from Outer Space or have weird powers etc. Very possibly ahead of its time.
- Traveller: The original science-fiction RPG
- Trinity (Aeon)
- Vampire: The Masquerade
- Werewolf: The Apocalypse
- Mage: The Ascension
- Wraith: The Oblivion
- Changeling: The Dreaming
- Kult: Biblical based horror game
- Top Secret: Espionage based game
- James Bond
- Twilight 2000
- Champions: Superhero game
- Call of Cthulhu: A game based on H. P. Lovecraft's novels
- Hong Kong Action Theater: Game that seeks to recreate Hong Kong action movies
- Feng Shui
- Unknown Armies: Horror game focusing on modern "sorcerors" competing to ascend to a higher-plane
Steam Punk/Steam Fantasy:
Wild West Games
- DC Heroes
- Golden Heroes
- GURPS Supers
- Marvel Super Heroes
- Villians and Vigilantes
Generic games with multiple settings:
- The Gryphon
- Journal of the Traveller's Aid Society
- The Last Province
- The Space Gamer
- White Wolf
- Alarums & Excursions
- Demons Drawl
- The Guildsman
- Tales of the Reaching Moon
- Telegraph Road
- The Whisperer