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If it's a game first released on this gen, I'll go Metroid Prime 3. An excellent ending to a trilogy that combined Metroid's signature exploration with a more focused story. The inclusion of the moveable gunship was a great improvement and one that I hope sticks with the franchise going down the road, and Hypermode worked wonderfully as the biggest new "gimmick." Hypermode allowed for another level of strategy and planning with choosing to either deal damage or conserve health, and the invincibility surrounding Hypermode made the player's timing of it all the more crucial (especially when enemies gain the ability to knock the player out of Hypermode).
Outside of that, it's pretty much all great as well. The Wii remote controls work wonderfully, the action (and particularly the boss battles) are all excellently designed, the music is top notch, and the graphics still look better then some late gen 360 and PS3 titles. The only big complaint I have is that the game never explained that "Normal" difficulty for Corruption was toned down significantly from other normals in the past, and players should've started on Veteran if they had any sort of experience with Metroid.
