This guide is based around my experiences with messing with the game's files on MY configuration. This means that results may vary.

1. Install BMouse http://swisscm.duke4.net/
* check ReadMe for installation instructions
* open "dosboxBlood.conf" and at the end of document, change "blood.exe" to "bmouse.exe launch blood.exe"
* be sure to change the sensitivity (I'm using x30 and y-90)

2. Install DOSBox v0.74 to a different directory and then use its files to overwrite the ones in Blood installation folder. This will net you about 5 extra FPS.

3. Open "dosboxBlood.conf" and change:
fullresolution=0x0
output=openglnb
aspect=true

Explanation: "fullresolution=0x0" will stop the screen from stretching to a widescreen resolution and preserve the 4:3 aspect ratio.

OpenGLNB is the only output method that can preserve the 4:3 aspect ratio and maintain the sharp image. Here's a rundown of other modes:

Overlay - Crashes a lot.
OpenGL / Direct3D - Same as OpenGLNB but the image is blurry.
Direct3D / Surface - Image is not stretched to the largest 4:3 resolution.

Check the comparison between OpenGLNB's crisp image and other outputs' blurriness.

It's best to change the graphic mode via the conf file because GOG's graphic mode setup is buggy and sometimes doesn't apply the changes.

While using OpenGLNB you can have a working vsync if you force it in the graphic card's control panel. It can make the game a little laggy though. If you run the game and there are flickering DOSBox windows at the borders, just close all desktop windows and try again OR try forcing antialiasing.

As far as I can tell, "aspect=true" affects only FMVs. It makes them preserve the 4:3 aspect ratio.

4. Change ingame resolution to 640x480. The visual difference between 640x480, 800x600 and 1024x768 is almost not noticeable. But to compare the FPS: 640x480 gives you more than twice the FPS of 1024x768! Check the comparison between 640x480 and 1024x768.

5. The Blood's music files come in a very handy ogg format. This means that you can take GOG's soundtrack, convert it to ogg, rename it and overwrite the original Blood files. This basically doubles the ingame music quality.

Currently there's a bug which stops the ingame music from properly looping. To fix this issue, use this exe (required DOSBox 0.74):
http://www.gog.com/en/forum/blood_series/a_custom_dosbox_build_to_improve_the_support_for_blood

6. Be sure to bind "inventory_use" to something other than "Enter" otherwise loading a game will most of the time also use the currently equipped item.

7. You can turn off autorun in the "blood.cfg".

use the build from here
http://www.gog.com/en/forum/blood_series/a_custom_dosbox_build_to_improve_the_support_for_blood
to get improved music support

So far I didn't have any problems with music.

Qbix is referring to the bug in DOSBox where the emulated CD support would only play the audio track once, and not loop the way it is supposed to. You may not have noticed it if you get through a level quickly.

You were right, between all those screams, explosions and gunshots, I didn't notice the music doesn't loop. What a mess, this must be one of the worst re-releases on GOG. I added the appropriate info to the guide.

Thanks for the guide dude, it's helping me a lot!