Serious.sam.siberian.mayhem.merry.christmas.v1.... May 2026

: A unique cosmetic for the XPMR "Burner" Raygun, unlockable by finding a Christmas Tree and completing a special portal challenge on each of the game's five levels.

A "solid feature" of the (Patch 1.06) for Serious Sam: Siberian Mayhem is the permanent unlock for the Christmas Event via a new New Game+ perk . Key Christmas Features Serious.Sam.Siberian.Mayhem.Merry.Christmas.v1....

: The update adds Christmas-themed game menus, holiday music by Anna Lazarev and Ivan Špeljak Jitz, and festive enemy variants, such as Sirian Werebulls with glowing red noses and bosses dressed as Santa Claus. : A unique cosmetic for the XPMR "Burner"

If you were specifically looking for features from the update (which arrived earlier in August 2022), it added: Guide :: Christmas event: XPMR "Freezer" Raygun weapon skin and festive enemy variants