Open Source Game launcher
Many game storefronts also provide software to help consolidate and easily manage large game libraries. Software like, Steam, Origin, and Good Old Games Galaxy provides both a shop for games as well as easy management of game installs and updates. Other apps, such as Playnite, consolidates the libraries of all of these game launchers to become a sort of “meta launcher”.
Lutris is an open source gaming platform for GNU/Linux. It allows you to gather and manage (install, configure and launch) all your games acquired from any source, in a single interface.
Video game library manager and launcher with support for 3rd party libraries like Steam, GOG, Origin and Uplay, providing one unified interface for your games.
A cross platform, customizable graphical frontend for launching emulators and managing your game collection.
Nostlan is a high quality front-end launcher for video game emulators! Available on Linux, macOS, and Windows!.
QuickPlay is a windows powerful universal emulator 'frontend-of-frontends', which has support for countless emulators and systems, old and new, with a philosophy of being quick and easy for new users, yet comprehensive and flexible for old-timers.
jdMinecraftLauncher is a OpenSource Minecraft Launcher written in Python. You need Java and a Mojang Account to use this programm.
Legendary is an open-source game launcher that can download and install games from the Epic Games platform on Linux and Windows.No screenshots yet
Metropolis Launcher is a game launcher, emulation front-end and an extensive offline database of video game metadata thanks to MobyGames.
Metropolis Launcher is based on the .NET 4.0 Framework and runs on Windows XP/Vista/7/8/8.1/10.