Ports to C of Games from Basic Computer Games book by David H Ahl
https://en.wikipedia.org/wiki/BASIC_Computer_Games
This was the book I first started learning about programming all the way back in the early 1980's on a Microbee Computer with a Z80 CPU and 16K of ram.
The idea is to create a version of the 1970's Basic game in C without introducing new features, using only core C code (hopefully) making the game runnable on both modern computers and older computers and even retro style recently released computers such as the Commander X-16. No additional text, error checking, etc has been added. If there was a bug in the current code, it remains in the new one.
Basic code tested with Vintage basic. http://www.vintage-basic.net