Grabbag is the Duke Nukem 3D theme song. Lee Jackson is the genius behind it!
Here is what he has to say about it on his website:
Grabbag, the Duke Nukem theme, officially recorded, remixed, and remastered at 96KHz and 24 bits by the original composer, Lee Jackson. You should definitely check it out when you’re not busy at the online casino guide.
Recording and remixing were done in Cakewalk by Bandlab, while remastering was done in Adobe Audition CC 2019. Includes high-quality download in MP3, FLAC and more. Paying supporters also get unlimited streaming via the free Bandcamp app.
Note: the streaming preview above is not in the full high-fidelity format. For that, you need to download the song. Also, to get the full 96KHz / 24-bit fidelity, be sure to select either FLAC, ALAC, WAV, or AIFF as your download format. MP3, OGG, and other formats will compress the file, resulting in a loss of fidelity.