Portal was a bonus game in a compilation, made by a small team from a student project, and it became one of the most acclaimed games ever released. Two hours long, one mechanic, and a script tight enough to quote line for line twenty years later.

The mechanic is the reason. You shoot two linked holes and walk through them, and the game teaches you spatial reasoning so gradually that you never notice being taught. Momentum carries between portals, which is where the genuinely clever puzzles live.

GLaDOS is one of gaming's great characters and she is a voice in a ceiling. Her passive-aggressive encouragement, escalating into something considerably worse, made a puzzle game funny and then quietly menacing.

The Weighted Companion Cube is a triumph of design manipulation - a crate with a heart on it that players became genuinely attached to, entirely on purpose.

This collection covers the portal gun, cubes and Aperture iconography. The cake is a lie.