So there is Linux gaming, you’re saying.
What is there are Linux users playing Windows games.
There used to be one, sadly the likes of Loki Entertainment are now gone.
Not a windows game.
Amiga games running on UAE on GNU/Linux are still Amiga games.
b) Driving widespread adoption of gaming on Linux is a chicken and egg problem---without a significant market of Linux gamers, developers and publishers have no reason to publish native versions of their games on Linux, and without games to play, nobody is going to install Linux on their gaming system. Proton directly solves the latter problem, and may indirectly solve the former when Linux sees widespread adoption by gamers.