The Deadlock Empire is a nice little educational browser game for programmers .
It’s about concurrent programming and causing deadlocks. You play the role of a scheduler and execute multiple threads instruction by instruction in a way that multiple of them enter the same critical section.
I’ve recommended it to some of my students when I mentored the bank-account exercise and they seem to like it, too. It will probably be easy for experienced programmers but beginners might learn a few things.