The Serious Sam franchise will always hold a warm spot in my heart due to its frantic action, loose sense of physics, and over the top action. Sure it doesn't have the deepest of storylines but it does have some of the most epic boss fights ever committed to pixels.
The first screenshots from the latest iteration, Serious Sam 4: Planet Badass look great. It's easy to recognize the updated versions of existing monsters like the Knarr and Kamikaze and some of the new monsters look great. I'm interested to see what the addition of vehicles does to the game as well.