Originally Posted by New England Gamer
The way to find out though would be to try and purchase from your device. The app store won't let you purchase and incompatible app right off the bat that way but via computer you can download anything you want - compatible or not!
Typically, if the iTunes Requirements section lists the devices it is compatible with, that's what determines whether a game will download or not. I've been burned (luckily just a few times) by games that downloaded to my iPod Touch 2G and then wouldn't play.
I think there's some sort of switch set on the App Store that detects whether it should download and, if the Dev doesn't tell Apple to put it in the Requirements section then you could get screwed (even if it does download to your device).
Here's the requirements for this one:
Requirements: Compatible with iPhone, iPod touch and iPad. Requires iOS 3.2 or later.
It doesn't list 3GS, 4G, etc. so it will most likely download to any iDevice. I'll wait for confirmation on whether it runs on earlier devices before I bite on this one.