You're simply wrong, there are plenty of AAA games on Steam, GOG and the Humble Bundle for Linux. Plenty. It's just not the case anymore that you cannot game on Linux. Also, we're on 2017, 2015 is not old.

Here are some AAA games that I own, all running great on a Linux laptop:

    - XCOM: Enemy Unknown (the remake)
    - Alien: Isolation (impressive graphics)
    - Insurgency
    - Mad Max
    - Victor Vran
    - Portal 2
    - L4D2
    - Dawn of War 2
    - SOMA
    - Firewatch (awesome graphics)
    - Invisible Inc
    - Transistor
    - Divinity: Original Sin (impressive graphics)
    - Hand of Fate
    - Shadowrun & all expansions.

... and plenty more. I just picked some that I like (you won't see racing or sports games because I'm not into them), I actually own hundreds of games. Some newer, some older, some low spec, some hardware-demanding.

In this day and age, pretending that gaming on Linux is hard is just FUD. You may get the games later than on Windows, and not every game, but still there are plenty.