Portal 2 Update Adds Big Picture Support, Split-Screen And More - GameGuru
Portal 2 Coop Split-Screen - YouTube
Portal 2 Splitscreen and Online Co-Op Detailed.
Uhh wtf? What's happening here? (Portal Reloaded coop in split screen, as I can't find ppl. btw it's so damn confusing, and I've played the whole singleplayer campaign...) : r/Portal
The best split-screen games for PC | Digital Trends