I ended up writing my own Pac-Man on MSX with a twist that pills are ammo which you can fire at ghosts, instead of them running away. It was one of my first coding projects and I hadn't got into multi tasking yet, so everything paused while the bullet was flying until it either hit a ghost or wall. Drawing out all the animations on graph paper, to then convert to hexadecimal sprites was a lot of work.
Yet I'll vote for rogue as I played that a lot on 8086 PC. r.exe, just one letter, hours of fun. I never got very far as I didn't know English yet so had no clue what anything did except by experimenting. Capital letters were always bad!