Fan-Made Trailer

Official or not, Don't care!

After Siberian Mayhem Add-on for Serious Sam 4 came out (yesterday)

I couldn't help it

It's like with Doom Crossover, but Serious "Sam" Stone meets Hazbin Hotel Characters

Or better say, they meet him

Hazbin Hotel - Vivziepop

Serious Sam - Croteam and DevolverDigital

Serious Sam: Siberian Mayhem - Croteam, DevolverDigital, Timelock Studio