I know what the word means and that's why I'm wondering - the game is free. You don't need to pay/donate.
I think nf3 is saying (s)he won't play because DR is not open source.
Of course, most games here aren't, so it seems like a strange expectation to me.
Hello, Sendo; first of all, congrats and great job on your work like always! As for user nf3, just ignore them; looking at their comment history, they're just going around labeling things proprietary or not for some pointless reason. Keep doing what you're doing, Sendo.