Graphics
Motion Blur
Simulating the streaking and smearing that cameras capture when objects or the viewpoint move quickly.
Iconic Games
Zork
The text adventure that proved your imagination renders better graphics than any hardware ever could.
Mechanics
Fast Travel
Teleporting across the map because walking there for the 50th time stopped being fun 49 trips ago.
Technology
Physics Engines
Faking real-world physics convincingly enough that your brain does not question it.
Narrative
The Twist Ending
That final revelation that makes you rethink every single thing you just played through.
Based on infomaxxxing codebase