"We've rescued 16 people so far! Let's keep going!"
A fun cipher-breaking play mechanic overlaying a dark story that gets a prequel in "Visual DOS: Integer Overflow" from the same lovely creator.
(If you get a repeat stage, it doesn't mean that you've run out of new ones!)
This is a super cool and unique use of ZZT. The game is full of humour and keeps things interesting as you progress. Absolutely recommend.