Duke Nukem 3D

Duke Nukem 3D: Atomic Edition on Zoom-Platform

Unfortunately, Duke Nukem 3D isn't available on GOG; Zoom-Platform is a similar DRM-free store.

Duke Nukem 3D was built on the Build engine, which is an arcane and interesting piece of technology. EDuke32 is a multiplatform source port for the game, and can be built for Windows, MacOS and Linux; however, only Windows has downloadable binaries.

Installation: EDuke32

1. Install EDuke32. Download for Windows, or build for Mac/Linux. Keep the directory you install it to handy.
2. Place DUKE.RTS and DUKE3D.GRP into the same directory.
3. Launch eduke32.exe and choose the version of the game you added.
   
4. Configure from within the game.
   

The options aren't as robust as say Doom + Doom II, but it's playable on modern hardware and resolutions.