"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!)

Love NickCage

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.