I want to play Garry's Mod and Team Fortress 2 at the same time so when I get bored of one I can easily alt tab to the other and when I'm needed back on the RP sever I like to join I can go back then as well.

  • I haven't tried Garry's Mod and TF2, but you can definitely launch two games at a time. I even tried launching two source games (TF2 and CS:S) at the same time so it seems to be something specifically related to Garry's Mod. – Mr Smooth Dec 29 '11 at 8:01
  • No its not possible for two source games at the same time, you could play TF and some other game, though. – ordag Dec 29 '11 at 9:10
  • @FallenAngelEyes No. – ordag Dec 29 '11 at 11:46
  • Ignore my close vote, I'd misunderstood the question here. – FAE Dec 29 '11 at 11:53
  • Here's what I did I ran tf2 then I pressed alt+tab and it minimized tf2 and I ran gmod – user49448 Jun 1 '13 at 22:39

Steam doesn't have such limitation, but you can't play two games that use Source Engine at the same time.

  • 3
    Can you explain why we can't play two source games at the same time ? – Timothée Jeannin May 17 '15 at 16:51
  • Because when you try it complains that you can't (e.g. Portal 2 and Titanfall) – Nick T Jul 6 '15 at 6:43
  • This limitation may have existed six years ago, but we just tested it and, as of 2018, it's perfectly possible to have two very similar games open at once. – rosuav Jan 21 '18 at 6:23

Yes, you should be able to just alt-tab out of one game and open the other. This is a bit resource-intensive, though, so you may suffer some performance loss if you don't have a pretty powerful computer.

  • 1
    dual monitors? better than alt-tabbing if you do have the option. – Enigma Sep 20 '12 at 22:57
  • @Enigma - Possibly worse, if you're having to hold all rendering content in VRAM / RAM, and can't page any out - not to mention rendering everything on both screens. I mean, it'll depend on the game, sure, but I don't think you can definitively say that it's the lighter option. – Jeeva Jul 6 '15 at 7:32
  • Yeah I meant better in terms of human effort. On most accounts it would be more effort from the PC. – Enigma Jul 6 '15 at 13:52

I haven't tried this with Garry's Mod and TF2 specifically (I don't own the former), but there is typically no such restriction. In fact, earlier today, I accidentally launched two copies of DEFCON at once with Spiral Knights updating in the background!


Steam does not limit how many games you can run at once, however, you can only run one source based game at once. This is a limitation of the engine, not Steam.

  • Could you add a source for that? No pun intended. – Spidey Oct 28 '13 at 17:45

Yes, assuming that both (or all but one) of the games you want to run simultaneously are reasonably gracious about being switched out of context. But that's an issue with the games in question, not Steam.

Steam's only limitation in the mix is that it will only start one game at a time; as soon as the "preparing to launch XXXXX" dialog vanishes Steam hands over control to the game itself and you can start a second.


As others have said, only if it's not two Source games. But, many non-source games can be opened together (and you can have ONE source game and another non-source game). Steam doesn't really care, it mostly depends on the games. But don't try to open two really memory-destroying games at once. Unless you're using a supercomputer.

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