Hmm. I haven’t played this in ages and appear to be lost. I landed on Lava Land (or whatever it is called) and warped back to the last bit I’d got to. There was a locked door, so I backtracked a bit, found a new route, and opened the locked door from the other side. Erm.
That means I have no idea where to go. I thought maybe I needed to go back to the Celestial Archive, but there was nothing there. Decided to play multiplayer over t’t’t’tinternet instead, and found one person to play against who kept killing me with some homing shock wave thing, or with from-a-mile-away headshots. Bah.