Ok, the planet in LocoRoco probably isn’t the earth. Not unless you’ve been eating those special mushrooms again. However, you still save it by doing some weird stuff. So it totally counts. The Mui Mui (the blobs you shift around in the game) are a peaceful race, growing vegetables and singing to make their world all lovely. There’re lovers, not fighters. So when the Moja Troop arrives and starts fucking shit up, the Mui Mui don’t have a clue about how to defeat them.
Enter you, the player. You actually play as the planet in LocoRoco, tipping the useless blobs around the screen in an attempt to wipe out the Moja Troop. Obviously. The Mui Mui are pretty passive in all this. They just kind of hang around, being amorphous passengers, as you clean up the mess for them. In hindsight, it probably isn’t worth the effort, and you should really just leave the Mui Mui to die out. Survival of the fittest and all that… Plus, their singing is very, very annoying.