You are allowed to post a quality introduction with genuine effort.
Moments of you simply horsing around with friends, playing through a whole campaign/chapter (with bots), walking around oblivious and WOWING at that coke bottle are categorized as “Let’s Plays” and are examples of what’s not allowed. Unique being but not limited to: genuine speedrunning & survival runs, executing skill-based actions, or moments where things go horribly wrong (or right).
Highlights or videos of unique L4D gameplay are allowed.