Linux is not gaming friendly in general, like at all so far. There's been indication that this might change, but not for some time.
Yes, there are around 2500+ Steam titles that work on Linux, but many popular titles don't support Linux (GTA V, Witcher 3, Doom ect.) and need to be ran through software like Wine, which indicates unstable performance at compared to Windows at times or glitches, but should be stable if you have a good rig. All games from Valve will work on Linux if you play any of those though.
The rest are mostly indie titles or older games. As for the native Linux game library, it is much smaller outside of Steam, with most being yet again indie titles or Quake clones.
In general, if you're looking to game, Linux is not a good option at all (especially if you want to play AAA titles like Witcher 3, Fallout 4, Doom, GTA V). I would highly recommend investing in Windows 10.