I can recommend https://www.widelands.org/
Don't ask me how many hours I wasted with that, just to experience the wuselfactor. The mission is also quite fun.
Another good timewaster is https://7kfans.com/
But you'll probably only enjoy it if you played the original in your youth.
I replaced a handwritten lexer of a proprietary PDF library with a re2c generated lexer. Besides fixing a bunch of dormant bugs, the resulting lexer was much faster.
Also the state of c++ std regex implementations is pretty sad (at least it was the last time I checked) and if you just need to match with a few compile-time-known regexes, re2c is there for you to solve the problems.
While the words in the articles are public domain, the bits in the files are not. So to free the articles, you have to take the bits, turn them into the words and then encode those into bits again.
Another good timewaster is https://7kfans.com/ But you'll probably only enjoy it if you played the original in your youth.