Portal 2

Portal 2 wakes Chell after years of cryosleep in the middle of the crumbling Aperture Science laboratory, forcing her to once again face the passive-aggressive artificial intelligence GLaDOS in an expanded, more intricate puzzle concept built around portal guns. This time it's enriched with new mechanics such as gel surfaces that alter the physical properties of surfaces, jets of propulsion air, and laser bridges. Valve expanded the short, cult-classic concept of the first Portal into a full-fledged campaign with an elaborate, often unexpectedly moving story, joined by the character of Wheatley, voiced by Stephen Merchant.

New elements arrived at a carefully measured pace: each chamber first demonstrated a single property in isolation, then combined it with earlier rules, so the player constantly felt they had figured out the solution on their own. Descending into abandoned, decades-old levels of Aperture also explained, through the story, where this whole absurd institution came from. The two-player cooperative campaign, with robots Atlas and P-body, demanded flawless communication and portal synchronization, creating one of the best-designed cooperative puzzle experiences in the genre's history, appreciated even beyond the traditional Portal community.

A witty, self-deprecating script combined with elegantly designed puzzles made the game one of the highest-rated titles of the entire generation across all platforms. The PS3 version additionally featured a unique link to Steam accounts and cross-platform multiplayer with the Steam version, an unusual collaboration between Valve and Sony at the time. Portal 2 confirmed that a logic puzzle could carry storytelling just as powerful as big action titles, and it remains cited today as one of the best-written scripts in video game history. The game has also aged remarkably well: the clean, functionally designed laboratory spaces never depended on the graphical effects of the time, so even years later they look exactly as intended.