XEvil is a bit of a departure from the games posted so far, in that it is the first game designed primarily for multiplayer play, and deathmatch at that. There is, of course, a single-player versus CPU option as well, and a number of different game modes. The controls can be a bit awkward by today's standards, but it has some good ideas and a variety of fun weapons, items and characters.
If you were thinking the above screenshot looks entirely too colourful for a 1994 game, that is version 2.1. The 1.x series appeared as follows:
The early version pictured above only supported multiplayer by running multiple X displays, with the additional possibility of two players on a single display. Because X is a networked display system, other players can be on separate machines on the same network, with the actual application technically running only on a single machine. Later versions introduce "standard" client/server TCP networking, simplifying the process of getting a game going, especially with cross-platform users.
XEvil still has a web site too! However, we need to dig into the archived copies for the version history. It was originally written by Steve Hardt in 1994 for MIT students to use with Project Athena, then uploaded to the internet in 1995. Michael Judge handled the port to Windows. A later build for OSX appeared, but I don't see any clear credits for that one. It's also a PowerPC binary, so... less useful now.
The following video shows a single-player session playing the default "Levels" mode in version 1.5:
XEvil has been in and out of the Debian repository. As of the time of writing, it was packaged for Jessie (8), removed, then re-introduced for Bullseye/Unstable (11). If it's not packaged for your distro of choice, grab either the Debian package or the source release from the web site and give it a build. Or get the Windows version from there, if you aren't a Linux user.
More general information on old X games, including build tips can be found in the Old X Games article.
If the above video does not work for you, it is also available on my YouTube channel.