I stumbled upon this and wanted to share. A screenshot says it all...
Level 1 is simple, and it gets progressively more challenging (naturally). The game explains how each type of logic gate works as it introduces them one at a time. So it's actually a fun way for someone to learn the functions of logic gates, in an edutainment sort of way. Otherwise, you can geek out with an addictive puzzle game. You can play it for 2 minutes or 2 hours, which in my mind makes it the perfect type of puzzle game to have on the go. It's free, with no special permissions required.