I did frontend and WebGL development. It was back in the days when parallax scrolling sites and video on the web was still cutting edge. Especially on mobile. But even more so, WebGL was just recently supported on mobile devices in Chrome, so Google created this site to promote not just the movie, but also new tech.
Most fun was the games. I did a shooting game with nice physics, a turn-based multiplayer game with WebRTC in WebGL and a HTML side-scrolling storytelling experience.
Multiplayer games are always a lot of learning. Especially how to make them fun. Got help with the networking parts so I could focus on the experience and gameplay.
These immersive sites was very rewarding to produce, with seamless loading, transitions between 2d and 3d, integrated sound by Dinahmoe and stunning design.