An update on the Croteam website (thanks xxzen) announces their plans for a Serious Sam follow-up. Here is the first word on plans for a sequel to their fast and furious shooter that will use an enhanced version of the Serious engine, and will offer an escape from the Egyptian environments of the original:

After small but needed vaccations we are back with our regular Sunday development diary.

We can announce work on new game from Serious Sam universe. Right after finishing work on Serious Sam: The First Encounter, we started work on new game and upgrades to our Serious Engine. What we can promise in new game is: no more Egypt, new monsters, new weapons, cool effects, Serious playability tweaked to fit more players and still attract our established fan base. Along game we are working on upgrading our Engine and Tools with some new features, bug fixes and more elegant solutions for developers and modders.
On Tools note, one of big thing we are working on is Skeletal animation system for models (SKA). While allowing same numbers of monsters on screen without high impact on performance it will allow more versatile and smoother animations (with even higher polygon count) in game. Our model format will be changed (from expirience we got from our users and mod comunity) to more flexibile and easier to create format. When SKA is ready we will post full feature list with examples, help and tutorials.

Stay tuned for next instalement, when we will show more info and some images from new game.

Have a good weekend,

Admir Elezovic

P.S. there wont be Egypt levels in this game.