Alternatively: There are Multiple Endings in the game, and you need to fulfill the requirements in order to obtain the true ending.
Double Subverted: Never mind, it's still hollow. My bad.
Parodied: Alice starts complaining out loud about the ending, until the game gives in and delivers a proper ending.
Averted: The game has an up-to-standard ending.
Enforced: The publisher demanded that the devs concentrate on gameplay and put them into a very tight schedule, so as the deadline approached, they had to just whip together a lazy ending instead of the better ending they had planned.
Lampshaded: "That's it? That's the ending? Man, what budget were the game developers running on?"