Just created my GoG account, purchased and downloaded and installed BLOOD. NOTHING WORKS. I click on the PLAY ICON and nothing happens.

Any suggestions?

There's GoG support pages or the games forum for Blood.
https://www.gog.com/forum/blood_series

Can you provide more details? Did you install in Galaxy or from the offline installer? How are you launch the game, from Galaxy or from a desktop icon or from the executable file in the game directory? Does a process open for the game in task manager (if you're using windows)?

I just completed Blood. I installed it on an up to date windows 10 OS with the most recent offline installer. Worked like a charm.

Blood.... One whole unit... (Or was it Bloodnet?)

I tried to play this. No subtitles, the audio was incomprehensible, and 5 minutes into the intro i got bored to death...

You need a haematologist.

"Hi, I just bought an old car yesterday and now nothing works, what's wrong?"

Seriously, you need to provide way more info than that :D

Have you checked that your computer meet the requirement? What computer?
OS?
Install method - Galaxy or Offline?
Does any game work?
Any messages?
Tried re-installing? Rebooted?
Does Dosbox start directly?
Tried launching the game directly? Perhaps the shortcut doesn't work.
Have you downloaded, unpacked and installed directx9c? https://www.microsoft.com/en-in/download/details.aspx?id=8109

*Pics Related*

(Also thanks for the chuckle)
============================ If it doesn't work and no one can help you could try BloodGDX/BuildGDX...they are programs written in java that allow the game to run on some PCs & add some other features as well.
(The pics attached are for the guy above, btw, not to or for you yourself)