Just about anyone has played Half-Life 2 at this point and maybe even played Synergy... but did you know there is a native version for Linux?
Play again as Gordon Freeman and escape the city through canals, sewers, beaches, Ravenholm and City17. You aren't alone, not only is the rebellion there to help, but you can bring a few friends along! Enjoy the physics puzzles, jump tricks, hover jet and buggy with a few friends... you never know what is going to happen.
Synergy installed without issues and I was able to host on a LAN and my other PCs joined easily. You use the classic listenserver interface where you pick a level start the game. There have been a few unexpected bugs which is honestly... expected with mods. You can not save the game either, but Synergy packs an autosave and autospawn feature so you all can play cooperative together without loosing a lot of progress.
Mint 19.3 64-bit
GeForce GTX 1060 & GTX 950
Nvidia 460 & 450