I didn't buy into the hype of HL2 at the time, I didn't like the more serious tone it took compared to the original and I hated the slimy alien spiders and some of the other monsters. I think HL3 was never made because the expectations were too high and Valve were clueless where to go with HL3 - the ceiling of this (sub)genre had been reached.
I voted for Spider-Man 2 although I played it for the first time just a couple of years ago on emulator, it is a very special game and IMO is better than 2018.
Deus Ex (2000) - a game that pushes the boundaries of what the video game medium is capable of to a degree unmatched to this very day.