Crysis 1.
This game may be older than my grandmim but as far as a game, this one has aged well beyond the years since it still is one or the more beautiful games around. Hell i can confidently say that people can still use crysis 1 as a means of gauging how good their computer is.
FEAR: First Encounter Assault Recon
Up to this day, i still see FEAR as one of the finest fps games around mainly for its really solid gunplay mechanics, punchy as f""" sound effects, and the incredible mix of japanese style horror in a very western first person shooter. Its amazing how the first game is still the best one since the sequels couldnt really hold a candle to it and dont get me started on FEAR3