AssaultCube VS Warsow

Assault Cube, is usually recommended as a starting point. Source: about 1 year ago

Assault Cube should run on pretty much anything, and it's free. https://assault.cubers.net/. Source: over 2 years ago

Pretty sure AssaultCube has LAN (not sure though - https://assault.cubers.net/). Source: over 2 years ago

Assault Cube is a simple old, free FPS game.Kinda counter strike like.It runs on anything: https://assault.cubers.net/. Source: over 2 years ago

If you haven't heard of it, AssaultCube is a really good, lightweight game that functions as a basic FPS and is quite easy to start out in cheating with, but also has the ability to cheat in more advanced functions like aimbot once game hacking comes easier, and there are hundreds of tutorials on getting started with cheat engine in AssaultCube. (Note that while there is Online mode, stick to singleplayer since... Source: almost 3 years ago

Cube Engine 1 and 2 touted as the smallest (in terms of file size) FPS Multiplayer game. It's also free. Unknown if the community is still booming as I have not played it in a long time. Eh while we're at it there's also Warsow but this one I know the community isn't as great as before. Source: about 1 year ago

I'd you want something a little more advanced but straight forward I highly suggest Warsow. It's a free first person arena shooter that plays very much like Quake. Source: about 2 years ago

Warsow is also quite good and very close to late 90's shooter's idea of multiplayer https://warsow.net/. - Source: Hacker News / almost 3 years ago

Playing games is part of who we are as humans. Ditto for making games. From Nine Men Morris to Shattered Pixel Dungeon, Mindustry, and Warsow, people have been making and playing games for free. We don't need a games industry in order to have games. Source: about 3 years ago