So I'm always looking for more games that follow the Metroidvania formula. Everybody seems to have a different idea of what exactly makes a game a Metroidvania. In my mind, the most important elements are a side-scrolling point of view, one large open world that allows backtracking, and the acquisition of new items and abilities that open up that world little by little. By this definition, non-CV and non-Metroid games that qualify as Metroidvanias are games like Goonies 2 on the NES and Shadow Complex on XBLA. I'm fairly sure I've played others, but I can't think of them off the top of my head.
So I was wondering what other games are like this. I've got my eye on Cave Story and La Mulana, but haven't tried them out yet (I don't believe La Mulana has been released yet on the Wii, but it's coming). I've also heard that Scurge: Hive on the GBA and DS is a Metroid clone, although it's not a sidescroller. Some people are calling Soul of Darkness on the DSiware a Metroidvania, and while it's very reminiscient of the later CVs, it's strictly level-based, not open-world.
Does anybody know of any other games like this? Any recommendations?