My guess is that if they would accept donations, they could be issued because of commercial use.
They deserve for sure for the job (Although I couldn't pass from selecting language screen. But that's probably this old PC)
Viewing post in It's there any way to donate to creators of RotT?
Well I managed to pass the language .... by clicking on screen center
Moving pointer over languages didn't show any change
But then I started playing and after a while the screen was black. I could listen voices and see subtitles, and also when I move the mouse it shows the label when moving over the objects ... but the screen remains black
Hardware is a Dell Optiflex 380 running Windows 10 64bits. 4Gb RAM pentium Dual Core 3.20Ghz
The computer is a bit old , I bought used 4 years ago, and runs quite slow, so probably is there