Portal 2
| Year | 2011 |
|---|---|
| Release platform | PC |
| Genres | puzzle |
| Developer | Valve |
| Country | USA |
| Era | Today, 2010 to 2026 |
| Importance |
Why it matters
The co-op campaign was written separately from the single-player one: two pairs of portals make puzzles that are impossible for one person.
