Storytime! ...Sober, more or less awake and still clueless i tried my luck again today.
I found out that if i lower the resolution a lot, i get a (kinda) normal looking screen. Not really playable, but at least i didn't had to guess anymore where to click if i wanted to exit the game.
I also found this thread by simon_doe: https://forums.elementalgame.com/424974. Since i still have the same missing-graphic-bug, i hoped the two where somehow connected, so the workaround sratner and DGB246 suggested might help me with both bugs. Sadly i'm the Rincewind of computerwizardy. Even with DGB246's instruction and spending quite some time searching, i couldn't figure it out.
Allready slightly frustrated i tried that automatic win-compatibility-mode. Not that i really thought it would help, but hey, couldn't hurt eiter, right? ...Well, it did hurt. After testing something Windows suggested for some reason i should try the game in the WinXP-mode. Sure, go on! ...Now i couldn't even see the startmenü anymore. So i started the game again the normal way and (wooho!) the menü was back... At least partly... With strange colors... And more on the left side than it should be. Looked a bit scary.
After that i decided to install anew. Again. Buuut i couldn't. If i tried, i got that "Could not access network location no$key" -error... Ok, let's delete the game-files manually! ...Still the same error. I googled it, which led me back in the stardock-forums. That error seems to be an familiar one around here. An easy solution to it i didn't find tho.
In regard to the little mental health i have left, i probably should stop searching anyway... That's some nice weather out there. I think i go for a walk.