... is that most iconic of geek pastimes. Armed with a handful of dice, you can put yourself in the shoes of a daring adventurer (or anyone you can think of, really) and work with your fellow players to overcome the challenges set in your way, as told by the game master, or GM. Since you only have to describe what your character does - or tries to - the possibilities are endless (but if you just want to stick with the age-old plan of killing things and taking their stuff, that works too). It's a fun, cosily social way to spend an evening now and then.
Various settings falling under the umbrellas of Dungeons & Dragons and World of Darkness.
There are probably a handful of tabletop games in progress at any given time, but attempting to list them and keep such a list up-to-date would be a tall order. Your best bet for getting into a game (or indeed running one) would be coming along to socials, getting involved, and getting to know people. That way, when they're looking for players, you might be asked if you want to be one of them, and if you're wanting players for your own game, you've got people you know to invite into it. :)