Two robots enter, both robots stay, only one has a slightly
elevated head. Minecraft craftsman Sethbling has recreated the
1964 sensation that swept an easily-amused nation, Rock'em
Sock'em Robots.  The classic two-player big robot battles comes
to life in Mojang's pile of virtual building blocks, using a
rather ingenious little pressure plate mechanic to simulate the
pulse-pounding battles of the original game. It's red versus
blue in its earliest form, the movable though somewhat janky
object versus the other movable though somewhat janky object.
Back when I was a little kid Rock'em Sock'em Robots would amuse
us for whole minutes at a time, after which we'd start breaking
bits off and throwing them at each other. I suppose you could do
the same thing with the Minecraft version. Download it yourself
via the link in the YouTube description and find out!  Rock 'Em
Sock 'Em Robots in Minecraft [YouTube]