Monster of the Week is a good horror game in a televisual style like X-Files or Supernatural Tales from the Loop can be used to run a Stranger Things style horror game with kids as the protagonists Mothership is for space horror like the Aliens series or Event Horizon

Fall of Delta Green and Trail of Cthulhu both rework the original Delta Green and CoC game engines to use Gumshoe instead which is a much better system for investigations.