I was googling for ZX81 screenshots last night and came across a nice game called Pipes by Fernando Miguel Barletta. I've used the forum search and haven't found anything about it so I thought I'd post it up.
PIPES 4K

Author: Fernando Miguel Barletta
Platform: ZX81
Download: PIPES4K.zip
This is a classic puzzle game in which you need to create a path to take the gas out of the maze. Every 5000 pts. extra life and 20 seconds extra time. The game ends when you lose all your lives. Move with the cursor keys and release gas with "0".
http://starbase.globalpc.net/minigame/index.main.html
