For about 6 months I've been playing my brother's copy of the original DOOM and DOOM 2. He purchased it on Steam, however there is no DRM lock-in on the actual IWAD gamefiles (all that's required to play the games).

I became curious, at what point is it considered piracy. Lets begin with, I am playing it on his computer whenever he authorizes me to do so. Surely that can't be illegal. Later, I make a separate user account on Windows to play the same game (Steam has a feature of "Library sharing" on the same computer).

Lets then say that I install Linux on his computer and play the same game, just from a different OS and user account. Is that still legal? Its still on his physical computer, and we cannot both play it at the same time due to there only being one computer. The instance of Linux is entirely there for me, not something he cares to use.

Later I clone the Linux partition with all my files onto my own laptop, and play DOOM from there. At this point, we have 2 separate computers with the same exact original copy of one game. I'm guessing that isn't permitted by the EULA (not that anyone cares).

My question is, where does the law draw the line? At what point does it become against the license policy?

PS: I did actually end up buying the entire series, because I decided to record the MIDI music turning them into MP3's (and FLACs).

I am located in Canada, and forgot to metion I am playing this via source port "GZDoom" licensed under GNU GPL3+ and MIT. Only the gamefiles (IWAD's) are subject to standard copyright.

  • 1
    Hi Nick, can you add a jurisdiction to your question. Answers can vary based on your country.
    – Andrew
    Commented Jun 4, 2020 at 15:41

1 Answer 1


At the point where you copy the game files, including the WADs, onto a new machine the original licensee (your brother) does not have access to, you are infringing copyright.

Merely copying the files onto a Linux partition won't constitute infringement as it's the same commercial software on the same system, just with a different OS (IIRC correctly the Steam version of Doom uses DOSBOX, a DOS emulator, to run the original code on both Windows and Linux. The only difference between the Linux and Windows versions are the DOSBOX builds, and DOSBOX is open source software that permits this).

To get it to actually run on Linux, you'd need to either get a source port or a copy of DOSBOX (both are free to download), but neither actions would change the legality of it.

  • Forgot to mention, I was playing it via GZDoom (and experimented with crispy-doom). Additionally, what if I hosted an SMB file server from my brothers computer, and linked the WAD files to GZDoom on my laptop. If i did it in a way such that the WAD is never entirely on my laptop (not even in /tmp), and since they're small it shouldn't be a poor gaming experience. Is that still piracy. If so, is it permitted to stream the game from his computer, even while he is using the computer at the same time (it wouldn't take much resources) Commented Jun 4, 2020 at 18:46
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    Distributing the WADs via SMB is no less piracy than distributing it via torrent. Your brother isn't licensed to redistribute the game via any means. Piracy via streaming is still piracy. Besides, the entire WAD needs to be on your computer at some point, as it is loaded into memory.
    – 520
    Commented Jun 4, 2020 at 21:05
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    @520 Steam does actually let you install the game onto multiple computers from your account and also literally lets you stream it from your computer to other computers that you are logged into. That is definitely different than streaming it or file sharing it through some other means, primarily in that it allows multiple people to play the game at the same time, but I thought I'd clarify that for people who aren't familiar with the platform
    – Kevin
    Commented Mar 22, 2022 at 18:46
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    @Kevin Those are completely different in terms of legality.
    – 520
    Commented Mar 23, 2022 at 19:45

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