My jam entry is set on a obscure (fictional) computing device from the 70s. I made a rather technical, possibly a little humorous manual to go with the machine as part of the jam, and then obsoleted the need to read the manual by adding a (much less humorous, due to lack of space) in-game tutorial. Though the tutorial was definitely the right idea, I'm slightly sad that no one reads the manual. For fun, inspired by TIS-100, I've made a more "authentic" feeling version my manual. Here's a page:

And, if competitively writing multithreaded assembly programming for a ridiculously limited piece of hardware sounds like fun for you, check out my entry, QPCA-77A.