Games don’t get old, people just realize they’re bad years down the road.
There are several games from the 90’s and 2000’s that are still a blast to play in current year (Quake, Banjo-Kazooie, Halo CE, Jet Set Radio, Super Monkey Ball). They hold up because they’re great games. If they ever got “old” or “outdated” then I have to question if they were ever good to begin with.
I’ve never played Half-Life 2 yet, but from what I’ve heard, its FPS mechanics still rival that of FPS games today.