atmosphere, one of the most impactful aspects about a game, i love games that have sometimes little to no direction given to the player, a strong musical soundtrack *or lack there of* in some cases.
a list of games that portray these aspects are
Ico
LIMBO
Journey
Dark Cloud
Year Walk
Ecco the Dolphin
Sewer Shark
Vectorman
ect.
they are very powerful in the fact that they play at emotion, with small bits of music in a Desolate empty space take Ico for example at the start you are alone with only the sound of the wind and the candle flicker as backdrop giving you a cold along feeling as you venture though that castle till you meet the girl.
limbo takes a different but similar take, as it is both visually dark and creepy and the sound track is mostly industrial sounds like metal clanking and such.
Journey is just an awesome the music is a calming companion along with you for the ride as well as the kind of open world aspect.
they are just beautiful examples of game play at its finest for me