AssaultCube might be a bit more popular than Unvanquished. We know about 5 links to it since March 2021 and only 4 links to Unvanquished. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
I would recommend Unvanquished instead. It's basically the same game but FOSS, much more polished, and there's a small but active community. Servers are often empty, but people will eventually come if you join one and you can play against bots in the meantime. Source: about 1 year ago
I enjoyed Tremulous as well. There's currently a sort of revamp (ignoring GPP/Trem 1.2), called Unvanquished. https://unvanquished.net/. Source: over 2 years ago
Unvanquished the fork of Tremulous (who's not developed anymore) could fit. Source: almost 3 years ago
You're probably thinking of Tremulous, which is also forked as Unvanquished. Started life as a Quake 3 mod if I remember correctly. Source: about 3 years ago
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: almost 3 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
Tremulous - Tremulous is a free, open source game that blends a team based FPS with elements of an RTS.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
PunchLab - Track the strikes you throw at the punching bag
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Timerly - A real interval timer
Unreal Tournament - Unreal is a series of first-person shooter video games developed by Epic Games.