It's a massive fic fest spread over the summer with several rounds, one of which collaborative, where teams devoted to ships create the best fic/artwork/cupcakes/songs/other. Ships are defined according to quadrants, but they allow multiship as being different quadrants (frex, Feferi/Eridan/Sollux wouldn't have to have everyone in a heart orgy). They don't allow flipping.

here (http://hs-olympics.dreamwidth.org/) is the dw comm, with the rules and everything explained. here (http://hso-announce.tumblr.com/) is the official tumblr.

I didn't participate last year (not being in the fandom), but it sounds really exciting.