The most popular:
- Unreal Engine: by Epic Games.
- Unity: written in C++, developers use C#
- Frostbite Engine: EA's in-house engine. Games: FIFA, Need for speed, etc. Mass Effect used it for Andromeda but went back to Unreal Engine after that.
- Steam (Valve)
- Epic Games
- Ubisoft Connect
- Origin (EA)
- GOG Galaxy
- Google Stadia ($9.99/mo with individual game purchases)
- Nvidia GeForce Now (free with limits and $9.99/mo)
- Xbox Game Pass Ultimate ($15/mo)
- PlayStation Now ($9.99/mo)
- Amazon Luna ($6.99/mo)
Gaming on Linux
Proton can port Windows games to Linux. Developed by Valve, a fork of wine.
Source code: https://github.com/ValveSoftware/Proton
Check if your Steam game can work on Linux: protondb.com
SteamOS is actually based on Linux.
Stadia is built on Debian Linux servers and Vulkan is their graphics API.
Open Sourced Games