The first two are largely the same FPS experience, just in different locales. This collection comes with three separate titles-Serious Sam HD: The First Encounter, Serious Sam HD: The Second Encounter, and Serious Sam 3: BFE. In this series, Sam “Serious” Stone takes a Terminator-like trip back in time to lead the resistance against an imposing alien force.
A serious gap in my PC first-person shooter experience was Serious Sam, which is cut from the same cloth as those other classics.
After that, the fun shooting with crass mannerisms of Duke Nukem 3D was alluring, if tawdry.