It works best if you open the browser window to full screen mode & let all of the images take a few moments to fully load. Unfortunately at the moment it's not suitable for iPads.
Crispian says: "Hover the mouse over the main line interchanges to take a closer look at the aliens, monsters and baddies."
Also if you hover your mouse over one of the 11 Doctors on the left hand side you can view their detailed line. "lock the pop-up window in place using the “s” key, so you can scroll along and view the full line" says Crispian.