User blog comment:The Mysteryous user/Icebreaker: A Viking Voyage for Android devices!/@comment-24682750-20130725000422

Or perhaps they could even give away for free the acquiring of the game itself but add prices to the level packs. So then, once somebody has got the game, they will have the first level pack unlocked which I think was Hammerfest, but once having completed it they would have to spend money on the next level pack, Troll Marsh.

It is just an option anyway but maybe it is far of being possible.