I was excited to hear about the Giantslayer Adventure Path. I figured this would be a good time for Paizo to produce the official rules for the "Shadow of the Colossus"-style combat that I've seen so many users homebrew.
Do any of the volumes feature such rules? Has a previous Paizo product already done this and I missed it?
The Mythic Monsters: Colossal supplement from Legendary Games offers several options for climbing on larger creatures during combat.