Descent PC Coop Multiplayer Gameplay using DXX-Rebirth at 2560x1600
231) Copy contents off the Descent disc to your hard drive.
2) Download DXX-Rebirth for Descent 1 here: http://www.dxx-rebirth.com/ and copy contents to the same directory.
3) Run d1x-rebirth.exe and set your resolution, joystick controls, and enable Persistent Debris in misc options.
4) Go to Multiplayer. Have the host select host and the joiner select Join Game Manually and enter in the IP address.
Note: If the host is behind a router, open the 42424 ports or enable DMZ mode if you're having trouble connecting. You do not need Hamachi or any other LAN emulator for this to work. It worked instantly and had no desyncing during our two-hour session.
Descent is a highly recommended PC co-op game.
Occasional commentary is in this video.