.. yeah, I got caught up with this thing too. c_c There's an iPhone/iPad "game" for Nyan Cat now as well, although it's just a cat-flying-through-the-air-doing-nothing-else thing right now, but that's supposed to change sooner or later. It's quite worrying how crazy the Internet has gone for this thing.. but eh, I'm in it too now. :x Tempted to get a t-shirt..
Anywho, this is a Mega Drive cover of the original song, hence the intro bits being a little longer (can be found here). It fits quite nicely for Mega Drive sound channels, with just enough to make it sound full.
This is the 7-minute long version, rather than the original 2-loop version I did. Might as well just upload the longer version than two versions of this thing. :P