Godot

Godot is an MIT licensed open source game engine that can be used for free without any licensing costs. The Godot engine and Godot Editor both support Linux, and Godot also offers a headless server version of Godot to run on Linux for multiplayer games. Godot is the perfect choice of engine for 2D games, with 3D support as well, and offers easy 1-click one export to Windows, Mac, Linux, Android and iOS, with commercial porting services available for supporting game consoles as well. If your game is developed in Godot, supporting Linux should be relatively easy.

The Steam Deck is a popular Linux OS based PC for gaming. A guide for targeting the Steam Deck with native Linux builds is available on www.kodeco.com. The guide covers the process from start to finish, establishing a test project in Godot, setting up builds and transferring a game to the Steam Deck to test. While the guide specifically refers to the Steam Deck, most of the guide is applicable to targeting Linux in general for Godot engine users.

Unity

Unity features Linux support and can compile native Linux games. Recommended versions of Unity to use are 2017.2 or 2019.x, and to avoid 2017.3 and 2018.3. If you are using either version it is recommended to upgrade to 2019.x to avoid a Vulkan crash on Linux.

In 2019, Unity announced they will be officially supporting Linux for their editor as well, due to increased demand.

Unreal Engine

Unreal Engine has the ability to compile to native Linux and the Unreal Engine Editor is available for Linux as well. The Unreal Engine Editor requires an account on the Unreal Engine website. After signing up, you will need to follow these instructions to access the official Epic repositories, and to access the Unreal Engine repository. After following these steps, you can clone the git repository of Unreal Engine and compile it from source.

A video tutorial by Ben Tristem is also available to demonstrate how to get started.