This redecorated Transylvanian castle includes limited-time objectives and monsters decked out for the Halloween season. The free Halloween Horrors update includes a Monster Ball map. That's why the developer is launching the game's biggest update of 2018 with Halloween Horrors: Monster Masquerade. Tripwire Interactive is fully aware of how well its PvE horde shooter fits in with the Halloween season. The month of October marks the best time of the year to jump into Killing Floor 2.