This only works if their site gets views and the free demo gets plays. In my experience, apps in the App Store are primarily found through the App Store, meaning potential users won't hit the site first to try the demo.

The standard solution is to give away a bunch of levels for free and charge for additional levels using IAPs.

I'm guessing that demo is getting a lot of plays right now and they should capitalize on the hype that's being built.

Relying on the App Store is a good strategy for development firms that cannot build their own hype. So far, I'm guessing these guys are doing an okay job.

But I have zero data on any of this, hopefully they do and are acting appropriately.