|This is a /v/ related article, which we tolerate because it's relevant and/or popular on /tg/... or we just can't be bothered to delete it.|
Tabletop Simulator is, like its name indicates, a simulator which allows you to play in your computer different boardgames and tabletop games, in 3D, with all the usual objects and quirks you find in real life.
Let this sink in for a moment.
Yes, while we have always had games such as the Dawn of War series, Space Marine, Battlefleet Gothic Armada, there is this unique thing about the tabletop mechanics which have never been managed to get adequately reproduced in all the videogames made until now, either due 3D or fixed grids, the sensation just wasn't right, with Tabletop Simulator this is not the case, here you finally have the chance to stay at home while playing a tabletop game online, thank to Steam workshop things can be added, and you can save it so you come back later to continue the game.
Still not immersive enough for you? Turns out this game also has VR support. So you really can throw your dice and place pieces with your hands instead of your mouse. The only thing that’s missing is haptic feedback (which some ambitious VR techies are already working towards).
So basically, if you want to play real tabletop but you don't even have an LGS to go to (or you just want to play with your friends halfway across the country), Tabletop Simulator is a good alternative.
40k aside there is also stuff to play D&D and some other games, and the Steam Workshop allows you to add new stuff to the core game, with people already modelling Imperial Knights and other cool stuff. Many card games, including Magic: The Gathering can be played here, too!
To sum up... if you want to play some tabletop game, but you don't have money or opportunity... here you go.
Shhhh, don't tell Games Workshop this exists!
As of October 2018, nearly all Warhammer armies were taken down from game after Games Workshop demand. Not quite, they didn't take everything, and mods are returning! (Pfft, as if we can't manually download mods.)