Threewave CTF for Deathmatch Classic (unreleased) - The Slipgate Complex (full level walkthrough)
The Slipgate Complex is a map for Deathmatch Classic's cancelled addon, Threewave Capture the Flag.
Threewave CTF itself is a port of the Threewave CTF mod for Quake to Deathmatch Classic that never came out, but was leaked in 2003 with the Half-Life 2 beta and other content from Valve.
This map is another port of a Quake map that didn't appear in DMC. In this case, the Quake map is E1M1: The Slipgate Complex. It's cool to see E1M1 with a full set of new, DMC-style textures, with some Half-Life textures here and there too.
As far as gameplay goes, the red flag is at the start of the map and the blue flag is at the end of it. Unlike previous maps, a large amount of items, such as ammo, weapons, and yellow armor, have been placed in front of each flag.