Serious Sam Fusion 2017 is the best way to experience The First Encounter HD, The Second Encounter HD, and Serious Sam 3 in a single package under the same engine. Running the first two HD games under the SS3.5 engine feels like you're playing a re-remake thanks to the updated engine and textures, plus proper upscaled UI support for modern high resolution monitors.

Be sure to check out the Steam Workshop mods for SS Fusion. I highly recommend A Seriously Stupid HD Remaster (ASSHDR) as it adds the chainsaw from Second Encounter to the First Encounter campaign, and reworks the lighting and visuals of some maps to be in line with the original non-HD games.

Serious Sam Fusion 2017 is the best way to experience The First Encounter HD, The Second Encounter HD, and Serious Sam 3 in a single package under the same engine. Running the first two HD games under the SS3.5 engine feels like you're playing a re-remake thanks to the updated engine and textures, plus proper upscaled UI support for modern high resolution monitors. Be sure to check out the Steam Workshop mods for SS Fusion. I highly recommend A Seriously Stupid HD Remaster (ASSHDR) as it adds the chainsaw from Second Encounter to the First Encounter campaign, and reworks the lighting and visuals of some maps to be in line with the original non-HD games.