Believe it or not, philosophy puzzler The Talos Principle began life as Serious Sam 4 (opens in new tab). That's what Wes learned back in 2015, which gives you a sense of how long Serious Sam 4 has been around—as an idea/concept/rumour if not an actual confirmed videogame.
Well, actually, Serious Sam 4 has now been confirmed. Revealed at the Reboot Develop conference in Croatia, its full name is Serious Sam 4: Planet Badass and it has a teaser trailer.
Beyond that, though, we've not got much to go on. As suggested at the trailer's end, developer Croteam is expected to show off more at E3 in June, while a coinciding trailer blurb reads:
Serious Sam 4: Planet Badass reignites the legendary series and elevates the iconic full-throttle action, massive hordes of enemies, and explosive array of weapons to the next level. Please join Croteam and Devolver Digital at E3 2018 for the full game reveal and wishlist now on Steam for the latest news and update on Serious Sam 4: Planet Badass.
A newly-launched Steam page echoes all of that, too. Speculate away on what we might expect in the comments below.