Maybe it's just everyone dumping ice water on their heads to promote charity, but Icebreaker: A Viking Voyage [$0.99 / $2.99] going on sale seems awfully appropriate. And not only is it going on sale, it's completely free for a limited time as Apple's "App of the Week", likely in connection to developer Nitrome's latest game 8bit Doves [$2.99] recently releasing.
The rope-slashing, ice-breaking physics puzzler originally released under the Rovio Stars label, but has since transferred back to Nitrome and is now on the App Store under their label. Oh, and the Rovio site makes literally no mention of the game at all. Hmm.
Both the iPhone-only and universal versions are available for free, though there is IAP in the game. The reason for split versions is likely because of Rovio policy before they decided to start making universal apps instead of split versions. I'd probably recommend the universal version for obvious reasons. This is one of the better physics puzzlers of recent vintage, and has a fantastic high-res pixel art style that's actually kind of hard to notice unless you really look at it. This is well worth checking out at the free price if you haven't yet.