The Epic Games Launcher is so far behind on features compared to Steam it's not even funny. Epic chose not to try and compete with Steam on that front and to try and force users onto the platform with exclusivity deals and sweeten the deal with free games.
The one user-centric killer feature Epic has in their stack IMHO is the built-in multiplayer crossplay. Except it's not even exclusive to their store ironically (you do need an Epic account for it though).
Nostalgia drive engaged !
The Crusader series (No Remorse, No Regret) could have been built upon, with its famously cheesy live-action cutscenes.
The Quarantine series disappeared after its second installment, Road Warrior. Come to think of it, most mainstream vehicular combat games went away, like the Interstate series.
The Discworld adventure games (1, 2, Noir) were famously convoluted, but they did a pretty good job of adapting Pratchett's world into video games.
Finally I would have liked to play the initially planned sequels to Advent Rising. I have (probably rose-tinted) fond memories of that game, but hey, you asked.