I'm a fan of Quake 3 Arena mods. Many of these have become standalone games such as Urban Terror and Smokin' Guns.
Urban Terror (UrT) has a large player community and includes an updater to easily patch the game.
UrT has fun over realism gameplay. The models and weapons are based on real examples but movement is exaggerated to create a run-n-gun style of play.
http://www.urbanterror.info/home/
The team is working on releasing a new version of UrT called Urban Terror HD with updated graphics and game play.
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Smokin' Guns is a western style FPS that has unofficial support for Mac. Currently, the Mac binaries don't run on Lion/ML.
http://www.smokin-guns.org/
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Navy Seals Covert Operations is a Quake 3 mod similar to Urban Terror but with a style and gameplay similar to Counter Strike. The game shares lineage with Counter Strike given that one of the developers of the Counter Strike mod produced the first Navy Seals mod for the original Quake.
Navy Seals Covert Operations also works with Open Arena. Using Open Arena and the Navy Seals Covert Operations mod files, I have made a self contained application bundle using Automator that launches directly into the Navy Seals Covert Operations mod.
The application bundle needs to be placed in the /Applications folder to function properly given the limitations of the shell script run via the Automator application bundle.
To set custom screen resolution, launch the in game console using the ~ key. Then use the following commands:
/r_customwidth XXXX
/r_customheight XXXX
/r_mode -1
BTW, I don't continually host a game server so it is possible that you may have to start your own. This game doesn't supports bots and no servers seem to be online but it does make for some good LAN play if you have a group.
Download link:
https://www.dropbox.com/s/801xuhzv4mjba55/TrueCombat.dmg
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I also sometimes play CS 1.6 via wineskin. The only tweaking required is installing tahoma, corefonts, allfonts via winetricks to get good reliable game play. Other tweaks may add more improvements but I haven't tried any.
If you don't already have CS 1.6 or don't want to try using wineskin, CSS has a Mac version.
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UT2004 has a mod called Frag Ops that is similar to CSS. I haven't tried playing it given that I don't have UT2004 and haven't been willing to get it just to try this mod because I don't know if the mod still has a player community.
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