It's called Hohokum, and it will be out on the PlayStation 4, PlayStation 3 and Vita (although what you see here is on the PS4). You control a snake-like character while you explore worlds and discover new ones.
You help in-game characters and creatures locate items and other characters and creatures. Sometimes, you turn lights on for new discoveries. But I could hardly glean all of this on my own.
So let the game's artist — Richard Hogg — tell you a bit about his game, which I have decreed the most confusing game I've seen at E3. Also, super sorry about the audio quality of the video. It was a noisy day. But it's worth learning more.