Does this work for the iPod Touch or iPad?
 
Im thinking of getting either, but I dont want an iPhone
This game would be my first purchase

I think it works for both. I've only tried it on my touch.

It should work with all of them. I have an old ass iPhone (3G) and it runs it great. The new iPod Touch's outperform my iPhone, so you should be set (tech on the old ones wasn't that different either). 
 
I also don't know of an iPhone/ iPod Touch app that doesn't work on the iPad. Some are specifically enhanced for the iPad's bigger screen, but if not it will stretch it for you. 
 
By the way, totally get that game. I played it for 4 hours straight instead of sleeping a few nights ago. Its quite amusing.

Just as a reference, from my own experience of owning an iPad since launch day and loading a bunch of iPhone apps on it as well as according to Apple, ALL iPhone apps work on the iPad.

 @MatPaget:
 
All apps work for iPad.
Some apps are only for the iPad and will not work with the iPhone or iTouch.

Worked on my iPod Touch 4G

Played in on my iPod Touch 4G, no issues whatsoever. Should work for the iPad as well, just with not-as-high resolution if you scale it up.