Communityevents - need help

Last year I started a thread about games with special Halloween events. This year I decided to create a seperated thread (actually only in german, but everyone will understand the overview) at steam with an alphabetical listing and one overview for special dates like Halloween, Christmas etc. Unfortunately its a lot of work to find games and their events. So I hope that the community can help me and give me hints about games and events. For me its enough if you name the game and, if possible, the event, so I can look for more informations by myself. Thanks!