You aren't on an island; you are on a continent. That's why you flew it was over mountains, trees, and lakes; instead of oceans, and seas. Also the problem with claiming a land is having the power to control it. You could say all of the unseen world is yours, but that isn't going to matter if you don't have anyway of watching over it. As for it as a game idea it sounds boring. What sounds like more fun is exploring ancient ruins for powerful magical items and artifacts; you know the things adventurers do.