Fond memories of a summer spent creating custom puzzles with Load Runner's edit mode. wikipedia 
YOUTUBE 72k1ZYp83tc Apple II version of Lode Runner from 1983
This memory was triggered by looking at Joshua Bennuck's version of tixy in Pico-8.
See tixy.land site
More about Pico-8 wikipedia
http://wiki.randombits.xyz/assets/pages/tixy-in-pico-8/tixy.html