@lupyuen Assembly was before my time, but I used LC-3 when teaching a computing course. Not all the students caught my enthusiasm, but it was a great way to demonstrate low level processes. There are some nice online simulators now. e.g., https://www.peterhigginson.co.uk/AQA/
@diyspaceprojects
What do you mean "before your time"?
Still used. Maybe not complete systems/games, but quite a lot to get embedded processors up and running.
@lupyuen