The ever-benevolent folks behind the Humble Bundle have released yet another weekly special, this time teaming up with Croteam to put forth a Serious Sam bundle.

The HD remakes of The First Encounter and The Second Encounter are available, and for those who pay more than the average ($3.88 at the time of writing), you can also unlock Serious Sam 2 and Serious Sam 3: BFE, effectively rounding off the trilogy in your collection.

Promotional video below the break!

Folks will also be able to grab the indie titles; The Random Encounter, Double D and Kamikaze Attack!, as well as an early beta test of the original game for nostalgic and historic purposes. As with other bundles, buyers may choose how their allocated between the Bundle organizers, charity and the game developers themselves. Here’s the bundle if you’re interested.

The most interesting aspect of this new bundle is the fact that all earnings for Croteam will go towards development for Serious Sam 4, slated for a 2014 release. Right now there’s not much to show except some promo art depicting a rather Max Payne-ish Sam in what appears to be Paris.