Survival of the Fittestpre-game can fall into a mixture of this and "Funny Aneurysm" Moment from time to time. A lot of threads come off as ordinary high school RP fare... until you remember this is only setting up characterizations for the actual storyline. As a result, sometimes pre-game threads can become particularly cringe-worthy as the game goes on, especially once you remember that the cute, likable character you've been reading gets broken and then killed, or alternatively, goes Ax-Crazy and then killed (bonus points if there is any Foreshadowing!).
Evolution has plenty of this, once you start thinking about the nature of the powers. A fair portion of them qualify as Body Horror, such as Johnny Marsh's transparent skin, Iris Landon growing mold from her mouth, Keira MacDonald's coughing up smoke, and Simon Matthew's flaming hot palms. A few abilities that don't sound too horrific still qualify; for example, Taryn Gregory having crystallizing blood sounds bad enough already, until handlers applied Fridge Logic on what would happen during certain times of the month. Add in the detail that even if these characters survived, most of them would be essentially be unable to live a normal life ever again, and Evo manages to be a deep well of Nightmare Fuel. After all, the concept essentially revolves around your average Ordinary High-School Student getting abducted, experimented on, given life-altering abilities, and then put through a death match. And all in the name of evolution.