Puzzle Quest 2.
I preordered Puzzle Quest 2 on Steam, because I loved the hell out of the first one, and reviews for the sequel were reasonably positive. And you know what? Fuck all those reviews, Puzzle Quest 2 is an awful abomination. Apparently it's the same developer, but you wouldn't know it. It ripped out half of the systems (crafting, capturing cities, taming monsters to turn into mounts/to steal spells from), and replaced them with basically nothing. The story in the sequel is nonexistent. Instead of having cool craftable gear that has a variety of effects, all of the gear just adds to a simplistic defense stat, and all of the weapons just do varying amount of damage, and the character don't have any sort of weapon proficiencies. It is terrible.
So yeah, never preordering games again after that.