TheBigCore: 1) Go to quakespasm.sourceforge.net

2) Click on "Manifestation"

3) Select Windows (32 bit) or Windows (x64), depending upon what processor your computer has.

4) Download and extract the files.

5) Copy the ID1 folder from your Quake 1 GOG installation and place it in Quakespasm's folder.

You should now have the ID1 folder under your Quakespasm folder.

6) Double-click on the Quakespasm.exe (not the SDL one).

Mouselook is enabled by default, so you will not have to do anything to configure that.

7) To configure controls, go to Options -> Controls

8) To enable music, copy the music folder from your Quake 1 GOG installation and put it within the ID1 folder.

For example: Quakespasm\ID1\music

The music files themselves can be FLAC, OGG, and if I remember correctly, mp3 as well.

If CD / external music has not been already enabled, go to Options -> External Music and set that to "On".