Final Level: Servant of Darkness
Why It Sucked: In Patapon, you play a deity in charge of banging your magic drums and guiding the little eyeball creatures in battle. Their quest is to reach the end of the world and gaze upon "IT," at which point their destinies will presumably be fulfilled and everyone will get cake. Only it's not, and the ending is as anticlimactic for them as it is for us—which is to say it's so bad, they decide to build boats and cross the ocean so they can find their real destinies.
How We Would End It: Blatantly setting yourselves up for a sequel is one thing, but it sucks when it comes at the expense of an actual resolution. This made it feel like the entire game was relatively pointless. Good thing we loved Patapon 2 and 3 so much.