Playing your non-Steam games on a Steam Machine
You own games on Epic, GOG, Amazon or itch.io. The Machine plays them — it just will not show them to you. Here is why, and what each way round it actually costs.
Sifter has not been run on a Steam Machine. Everything below describes SteamOS, which the Machine and the Steam Deck share; none of it is an observation of the Machine itself.
Why they never appear on their own
A Steam Machine boots into Game Mode, and Game Mode lists what Steam knows about. Steam knows about a program it did not sell you only when that program has an entry in its shortcuts.vdf file. Nothing writes that entry for you, so a game you bought on Epic is installed, playable, and invisible.
Everything below is a way of getting an entry into that file, or of running something that already has one. That is the whole problem — it is bookkeeping, not compatibility.
Check the game runs at all first
Two things stop a Windows game on a Steam Machine no matter how you launch it, and both are worth knowing before you spend an evening on setup.
Anti-cheat. Several kernel-level anti-cheats either do not run on Linux or are switched off by the publisher for it. No launcher, no Proton version and no workaround changes that — the game refuses. Sifter lists which anti-cheats work on Linux and which do not, from AreWeAntiCheatYet’s own data.
Proton. Everything else Windows runs through Valve’s compatibility layer, and how well varies by game. Valve’s own Machine rating for 1,846 games is the answer for a Machine specifically — it is Valve's own test on that hardware, not only whether the game starts. ProtonDB’s community tier answers a different question and the two disagree on purpose.
The ways people do this today
A launcher for the other stores. Heroic and Lutris both install and run games from stores other than Steam on Linux, and are what most SteamOS players use. They solve the running; you still have to get something into Game Mode afterwards.
A shortcut per game. Steam ROM Manager and NonSteamLaunchers write an entry into shortcuts.vdf for each game, so every title appears on the home screen with its own artwork. It works, and the cost is that the list is a snapshot: buy a game next week and it is invisible again until you re-run the tool.
Adding Steam itself. Nothing to do — Steam games are already there. It is only everything else that is not.
What Sifter does instead
Sifter is one library across Steam, Epic, GOG, Xbox, itch.io and Amazon, and a launcher for what is installed on the machine. On a Steam Machine it adds one entry to Steam — itself — so Game Mode opens Sifter and your whole cross-store library is inside it, including anything you buy after today. Settings → Add to Steam, in the desktop app, on Linux.
One entry rather than hundreds is a deliberate trade and it cuts both ways. You do not get per-game artwork on the Machine’s own home screen, and you do not have to re-generate anything when your library changes. If you want every game as its own tile, the tools above are the better answer and this page is not arguing otherwise.
Two honest limits. Steam rewrites shortcuts.vdf from memory when it exits, so restart Steam after adding or the entry is discarded. And Sifter does not get past anti-cheat or make an unsupported game supported — nothing does.
Get Sifter for Linux — free, and there is an apt and rpm repository on that page if you would rather it updated itself.