It's 1991, and things are bad. You're a guy with a wife, two kids, and a house. You're nearly broke, but you know that they'll be coming soon for what you've got left, hundreds of them.
The Castle Doctrine
Actually, it's not completely closed-source. Linux version ships in... source code. There is a file no_copyright.txt in it:
This work is not copyrighted.
Do whatever you want with it, absolutely no restrictions, and no permission
The game itself is definitely interestring, but way too hardcore.