OTOH there is Counter-Strike which turns 20 this year and is the third most popular game on Steam right now. Most of the changes to the core game since ~2001 have been about balance as opposed to adding new mechanics.
Someone who played the game over a decade ago could pick it up today and still play on mostly the same game on mostly the same maps:
de_cache 2011
de_dust2: 2001
de_inferno: 1999
de_mirage: 2004
de_nuke: 1999
de_overpass: 2013
de_train: 1999