First, I went ahead and moved your thread to the iPod forum, since this is decidedly not 'off topic', and therefore doesn't belong in the off-topic forum.
Secondly, be aware that the iPod Nano and iPod Classic do not run on iOS or OS X, but rather the old nameless iPod OS that is little more than a shell for playing music and some basic apps. There were some basic games developed for that iPod OS, but development quickly was abandoned once the more full-feature iOS devices came upon the scene.
That said, I highly doubt you'll see any games for the iPod Nano other than any basic ones that Apple pre-installs on them.
If the ability to play games is a priority, you might want to consider an iPod Touch instead.