Developed by 4D Rulers Software, Gore Special Edition is a remake of the full original GORE: Ultimate Soldier game with many improvements, new features, levels, weapons and more. And best of all it is completely free. A patch is also available. 
I'm not sure what type of engine it uses but I'm positive Spidey will find out 
http://www.4drulers.com/gore/index.php
—
[SAS]_Vet_Ade Veteran (Vet) 22nd Elite Virtual Regiment.
Downloading, but the TX servers aint too fast
My question is what does the game play offer over Quake, besides the class system? :-P. The collision detection was ahead of it's time back then, but not any more...
Gore was built around the AMP engine family, I'm not familiar with it but expect it is similar to the PAIN and Id Tech 3 engines that came before it. If they are using a modern form of AMP instead of the 2002-era one, it will feature much more modern processing facilities (lots more eye candy and still low system requirements) then the original release, but depending on how long the project has been going, they may not have completed the updates.
You can buy a development license for their engine, for under $10,000, which makes it a _very_ attractive product if you are starting company to develop closed source games. Most other solid game engines will cost several times that, and or a chunk of your profits.