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both on my win 7 home-pc (nvidia card) and win 10 work-pc (built-in video).

One of the main directories is empty ... could be the cause.

You should see the following structure (as I do on my machine when I unzip everything):

LD43_Data
--> a couple directories and a bunch of files
Mono
--> two directories
LD43.exe (run this one)
UnityCrashHandler64.exe
UnityPlayer.dll

Which directory was empty for you? Are you using the itch.io launcher, or just unzipping manually?
(Thank you for helping debug this!)

Manual unzipping gives:

AfterHours
--> empty

LD43_Data
--> a couple directories and a bunch of files
Mono
--> two directories
LD43.exe (run this one)
UnityCrashHandler64.exe
UnityPlayer.dll

It's strange that you have an Empty AfterHours folder. Can you try running the game through the itch app?
https://itch.io/app

gives the same problem.