A useful vote in 2020:
https://linuxgamenews.com/post/619211317433270272/serious-sam-4-will-not-have-a-linux-launch

The will to achieve it in 2013:
https://www.gamingonlinux.com/2013/06/serious-sam-4-is-going-to-come-to-linux/page=1

Realized with "Serious Engine" compatible for our OS:
https://www.pcgamingwiki.com/wiki/Serious_Sam_4

Serious Sam 4, will be the first Croteam game, made for Linux for sale without DRM on GOG!
It will also be the first Serious Sam that I will buy since my transition to Linux:-)

vote
https://www.gog.com/wishlist/games/serious_sam_4_linux

Prends mon vote... je suis en manque de bogues depuis que je touche plus aux jeux Bethesda. :)

Avec plaisir mon ami :-)
Je suis peut être naïf, mais j'ai confiance pour une grosse MAJ.
Ma seule incertitude concerne notre version, qui peut être retardé pour atteindre une finalité comme "No Man’s Sky" .

Yeah would be my first Serious Sam buy ever. Only played probably SS1 or 2 with friends before, was a very fun game. Let's hope they will bring it for Linux soon =)