The closest thing to an official mobile version was a cancelled project from 2009 called Serious Sam 2: Android Assault (a top-down shooter, not the FPS). That game was scrapped before release. Do not download any APK claiming to be "Serious Sam 2 for Android Exclusive full version" from random websites. 99% of these are malware that will steal your contacts or show infinite ads.
For over two decades, the Serious Sam franchise has been synonymous with adrenaline-pumping, chaotic first-person shooter (FPS) action. The name "Serious Sam" evokes memories of hordes of screaming headless bombers, massive alien arenas, and the iconic one-liner: “AAAAAAAAAARRRRRRGGGGGHHHHH!” download serious sam 2 for android exclusive
Today, this "exclusive" APK floats around shady forums like XDA-Developers and 4chan. It is often labeled Serious Sam 2 - Moga Exclusive.apk . The closest thing to an official mobile version