Portal.
The puzzles made you feel smart when you completed them, not stupid for struggling.
The dialogue was extremely well-written and the voice acting was a real treat.
I cannot recall any bugs, so the revolutionary new gameplay mechanic of portal travel was impeccably reliable.
Perfect pacing. Puzzles got harder/more complex, larger story unfolded naturally, neither too long or too short. Just the right amount of content and dialogue.
Great level design/environmental storytelling.
Fun song at the end.
Perfect game for user-generated content.
Portal does everything you could want it to, and Portal does it real well.







