Yeah so far I'd put it up there with the big boys of physics puzzlers. It's quality through and through.
Is this now permanently free and freemium? Or is it a temporary price drop? (Free) There sure are plenty of iap's including a couple of 'unlock' ones. Thanks.
Temporary (Apple App of the Week). The IAPs have always been there but, as I said on the previous page, they're totally unnecessary. The unlocks are just to unlock levels early, but you'll never use them as you'll want to play every level anyway.
The universal version is free again, down from $2.99. Still one of the best puzzlers on the App Store.