mwirkk: Darklands *is* a single-player game.
Are you asking if it can be played with a single-character party? Yes, you conceivably could, but it would be extremely difficult -- unlikely at best. If you attempt it, try on "easy" mode first. And save a lot; in which case, I'd' recommend you to use one of the numerous fan-made Saved Game managers, or do a lot of manual file swapping, as only 9 or 10 simultaneous saved games are supported in the game UI itself.
You're going to die a lot, though. And with just one character in your party it will be game over. Going through the Character Generation will force you to make trade-offs, so it's impossible to be superhuman or demigod-esque. What you could do is use one of the Character Editors to boost your stats and equipment up to max to give you best chance of survival. However, there is no such thing as invincible in the game, and certain attributes such as divine favor (DF) and quality of armor and weapons diminish with use and must be replenished or replaced.
You can find utility programs for Darklands on the GIO discussion group at
https://groups.io/g/darklands, or on the Darklands Domain at
http://www.darklands.net/index.shtml under files and tools.
-mwirkk
ooops, sorry for taking so long to respond to your very full answer, it will certainly effect my choice, thanks