If you like programming puzzles, I also recommend trying to write the littlemancomputer programs listed on this blog entry: https://blog.paulhankin.net/littlemancomputer/

They are fun in the same way as TIS-100 is fun, and especially the last couple (generate primes, sort input) are interestingly difficult.

Instructions and description of the machine on wikipedia: https://en.wikipedia.org/wiki/Little_man_computer

Online emulator: https://blog.paulhankin.net/lmc/lmc.html

[note: the blog post contains some minor hints, and solutions in links]