Portal 2 is a PC puzzle-adventure game famous for its ‘portal gun’ (which lets you create portals to teleport) and dark humor. For PC players who’ve completed the single-player campaign, what’s the most challenging puzzle you encountered—was it a room that required precise portal placement (like navigating moving platforms) or a puzzle that forced you to think outside the box (using gravity to your advantage)? How did solving it feel rewarding compared to other puzzle games? Additionally, the game has a 2-player co-op mode with unique puzzles that require teamwork—did you play co-op with a friend, and how did communicating (e.g., deciding where to place portals) make the puzzles more fun or more frustrating? Finally, Portal 2’s PC version has mod support for new puzzles and maps—have you played any user-made mods, and did they capture the original game’s tone and puzzle design, or were they too easy/hard?