A truly free and open source multiplayer shooter, no strings attached.
Have casual deathmatch matches on various scenarios.
Build your own levels with the ingame editor and assets that come with the game, or just play around and use it as a sandbox.

Features:

-Free.
-Open source.
-No pay to win.
-No ads.
-Modding friendly.
-Easy to use ingame editor.
-A big variety of levels and game-modes.
-Fully transparent development process.
-Community based, so everyone can make suggestions.

Some additional notes for all who actually read the description:

-This is an indie game and developed by mostly one person (me).
-This game does not use Unity or Unreal engine or any products bought from asset stores.
-This is an experimental volunteer project and not a final product, but a continous work in progress.
-This could/should have been labeled as early access, but I pressed the wrong button, so this option is gone now, deal with it.
-This project is an attempt to bring back the good old days.
-This is the attempt on offering an alternative for those who want one, if you are happy with the current commercial aaa titles, this game here is likely not for you.