In Nethack, playing on a Friday the 13th gives you a luck penalty. Playing when it's a new moon leads to a few interesting mechanical changes.

Friday after next is both October 13 *and* a new moon!

Are you gonna show off your Nethack skills on this spooooky rare day?

https://cdn.masto.host/mastodongamedevplace/media_attachments/files/111/178/689/682/433/060/original/e373e6f31c0eb670.png 

 @7e0cd0e2 @e4530301 nethack is one of those games I think more people should write about. I find its absence from various lists of all time important games sometimes befuddling.