I'M FIXATED ON SERIOUS SAM RIGHT NOW

For most people, I would say that Fusion is the most convenient way to experience The First Encounter, The Second Encounter and Serious Sam 3. As I've understood, there are still some quirks and bugs that aren't ironed out compared to other versions, but during my playthrough I didn't notice anything too gamebreaking. One slightly annoying example was cannonballs that fly around the map when shot at point-blank range. I can't exactly pinpoint all the differences in Fusion, but for example the movement is slower in SS3 than in the regular version of the game, and the Devastator doesn't have a scope.

On the achievement side Fusion is much better than the HD versions of TFE and TSE, since those two iterations mostly consist of multiplayer achievements that you would have to get from relatively dead servers. In Fusion on the other hand you'll get around 95 % completion just from a solo playthrough of all the campaigns.

All in all, after eight year of being in beta, it doesn't look like Serious Sam Fusion might ever get a new round of bug fixes or a proper release. Overall though, the convenience of having all games under one roof is something I can recommend to new players.

Double the gun, double the fun!