Final Fantasy XV
It was so close to being great in so many ways, but in the end all it manages is OK. You can definitely see the troubled development. Nothing fits together, and the story is an absolute wreck. They try so hard to make it seem epic, but it just feels disjointed and small. But throughout you can see this massive, epic story they were going for, and it just feels sad that it never lives up to it.
Basically the best part is the opening scene, and it's kinda downhill from there.