Yes!
Demigod Forums
If you're unable to select the Demon Assassin in single player, try running Demigod one time as administrator.
Then check to see if you can select him for single player. You do not need to run as admin each time to play, but running it just once as admin may clear up that issue for you.
This finally worked for me, but I had to actually connect to the internet, host a game and start it as the DA before he was selectable in single-player. Thank you very much for the tip 
Dash - I think this worked for me... eventually. Here's what I did. I couldn't get anything to unlock DA in single player yesterday. So, I uninstalled and redownloaded the game. This didn't fix it for me. Then I tried to run the game as admin, as you suggested. That DID NOT fix it for me either. Then, as a final step, I hosted a MP game, selected DA, then just quit the lobby (without every launching the game). Then, I went back to SP and I was able to select DA in skirmish and tournament. So, I think its a combination of things.
So, my advice to anyone still having issues unlocking the demon assassin in SP would be to.
Thanks, Dash!
All I had to do was login to multiplayer, then back out and he was selectable for me.
-Rune-
This worked for me as well. On a side note, i ran "DemigodLaunch.exe" as admin.
Okay I have run as admin and went into mp to host a game and then I could pick up the DA. However the Oculus fella is only pickable for the AI not for the player, and the above procedure dont work to unlock. Guess I will wait testing the game until this is sorted out.
Right - like syDaemon said, Aiyen, Oculus hasn't been unlocked by SD yet. If he's officially "complete" I think SD will unlock him before too long.
Hmmm yeah I had the same issue; I couldn't select DA in single-player, and because I haven't gotten into multiplayer yet, it sort of made me *cry*. Anyways, I just created a multiplayer game and set up an AI, backed out and he was selectable in single-player tournaments. Still can't pick him in single-player skirmish though, but I can still tear people up with him.
Thanks for the tip though; I'll see if it works.
I've tried every trick mentioned in this thread. Still can't select him in singleplayer. Work around is to play my singleplayer games through the multiplayer interface.
Dare I say reinstall if you have the time... then try my method again. I couldn't do a damn thing to get it work and might still be in the same boat w/o the uninstall, but i really don't know.
These two steps worked for me! Eventually.
The key step for me was logging into my online Demigod account and setting up a multiplayer internet game as the host. The Demon Assassin was selectable (and I selected him, of course!). After cancelling out of the lobby and returning to the main menu, the Demon Assassin remained available for other game modes (single-player, LAN multiplayer).
Just setting up a multiplayer game wasn't enough - I had to host an Internet game.
Can't wait to surprise my friends at our annual Thanksgiving LAN party - they don't know about the new character yet, and probably won't have him unlocked after patching. Heh-heh-heh...
[edit] Forgot to specify I am using Windows XP [/edit]
Thanks for the additional info Pacov! So far from reports it sounds like a combination of things are working for those that didn't have immediate access to the Demon Assassin in single player. If anyone still can't access him after trying all of this, please drop an email to [email protected] and we'll get you sorted out.
That's just mean. 
Make sure after you log into multiplayer that you stay logged in when you go back to the main menu. dont log out
hey i just installed the game yesterday via impulse (digital download), tried all the things out but cannot unlock the da in multi and in single play. but i can let the ai play him. what can i do, please help me! i`ve done all the things you say here, but nothing worked for me. i have vista 64 home btw, please help me!
okay, just changed the registryentrys from (0) to (1) now both new dg`s are unlocked! 
Yes
i ran it as admin, but it didnt work unitl i went to MP lobby and selected DA, then went back to SP
next day it was still there, so no need to repeat.
and hes really really fun
i tried all the tips here also and none worked. what unlocked him for me was playing 1 game online and winning. after that he was unlocked for single player and been enjoying him ever since. i doubt winning had anything to do with it though, it was probably just the act of completing a game online.
BOTH DG?!~where are those registry entry;s >:)
That picture was just from his bad side... 
I got the Problem, just the other way round.
I cannot choose him in online-games.
He's just greyed out, like Oculus.
So why is that???
Have you tried running the game once as admin?
Try closing Impulse and running the following file:
http://sd.stardock.com/curthendzell/fix_registrations.reg
Make sure to follow the link in Internet Explorer, as other web browsers will not handle the file type correctly. Once you follow the link, save the file and double click it to apply it. Then relaunch Impulse. You will need to re-login with your username/e-mail (either will work) and password.
If it still isn't accesible after that, drop an email to [email protected] to help get it sorted out.
I did all that. Also tried the .reg.
Didnt work.
Stardock doesnt answer me on my mail.
Just sucks.
Dash - perhaps there is an issue with the script that adds DA to players that have recently bought the game? I was in IRC when Nakor or one of you fellows was rolling out access for everyone that had already purchased the game, but he indicated that a script needed to run for new players as I don't think anyone automatically gets access when they buy the game. That might have changed, but I don't know.
Santa... what is the username you use when you play online? I see no online game history for your forum name.
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