Steam works on Linux . Linux is free.. (well you can buy commercial versions of Linux but there is no reason to)
Linux gamers should be pleased to learn that more and more popular gaming titles are becoming available. The GamingOnLinux website took at look at the most popular titles on Steam and discovered over half of the top 250 offer support for Linux. "Overall, out of the 250 most highly rated titles on Steam as reviewed by users, 132 of them have official Linux support. Compared with Mac which has 156, we're not far off there at all. Let's just remember how small the Linux gaming platform is compared to Windows, over 50% there really is impressive."
The only reason people don't try Linux is unfamilarity and profound advertising and brainwashing of the public by the M$ brand campaigners.
And it takes a tiny bit of reasearch to pick suitable performance version and features wanted (ie. Desktop environment, software wanted, etc.)
Switch your XP or Vista box to a suitable version of Linux (a version for older computers if your RAM less than 2 GB - otherwise I can certainly recomend what I use Linux Mint 18.3 Sylvia I use the 'Mate' version desktop for performance and least load..
Mint 18 series is simply a customzed offshoot of Ubuntu 16.04 - which the probably most stable and widely supported OS ever (IMHO).
I actually ran the 18.1 on only a p4 1.8GHZ and 1 GB RAM but its a bit too slow.
There is an actual SteamOS Linux that is made for Steam.
And some people like Sparky Linux for gaming, there are various other versions.
https://distrowatch.com/ is a good plavce to start your Linux learning.
and btw you don't need any commandline knowledge nowadays to use Linux
(although it helps for more advanced stuff - but you can easily pasteb commands from example pages from websites on subjects as needed)
..everything in most common Distros is done simply from a desktop interface just like Windows.
in fact the whole idea of Windows came from Linux.. (well NextStep really..)
The whole new so-called modern interface Windows grabbed onto for W 8 to 10 was available over a Dozen years ago on Linux or MAC.
(personaly I hate Metro-like stuff so I would avoid those anyway)..
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To sum up Linux vs Windows is sort of like;
You can buy a car from a dealer (Windows) that tracks your every move and seeks to controls your future (or even take the car away at some point) and share all your data with the whole of cyberspace, goverments, etc,,,
or u can get prebuilt a whole car with the engine you want, the interior the color, features, all for free (Linux Distributions such as Mint, Ubuntu , etc.) and even you can get a Truck or Semi or 4- wheeler or Van, LImo whatever or a Formula 1, stock car, drag racer, motorcycle, whatever you want to build, the sky is the limit.!!!