This is the earliest remaining screenshot; actually, it's two, showing the "blocked out" area of the first fire level and then the first-ever "arted out" level of the game. As this was the first level ever created at this level of detail, it was later refined, in April, 2001, I think.
In this early shot from May, 2000, you can see how the designers have roughed out the basic shapes for the area where the fire and water realms meet by the lava fall and the waterfall. The character in the shot was called, I think, Garret2, as that was Azurik's original name, and this was the second version of him. This version was never textured.
This shot from June, 2000, was the first in a series of "Screenshot of the Week" shots done for the team internally. It's a dramatic moment for Garret as he stares into the sunset. I think this is Garret4, the final "Azurik", untextured.
This shot from July, 2000, shows an untextured and unlit generator. Garret4 ("Azurik") has most of his texturing.
This is an early shot of the volcano level, with somewhat rough shapes and textures.
This shot from August, 2000, is from a "lost level". This was level "F7", the lava river. This was originally going to connect all the fire levels together. It turned out to be just way too friggin' big, and when we went from 33 levels to 22 levels, this was one of the ones that was dropped.
Another fire level that was dropped was "F5", inside the dam. There was a huge dam that kept back the lava river, and you had to go inside it and turn on all kinds of machinery. This level was pretty far along with working events and lots of textures when it was dropped for schedule reasons.
Another shot, from October, 2000, of the lava river and the generator towers sticking out from the lava, and the outside of the dam.
Another lost level, again, from October, 2000. This was an air level that was dropped for schedule reasons. It was one of the few levels that had significant art done before being dropped. Notice the "zero-cycle" bump mapping on the walls. (That means the embossing was done in Photoshop, not Xbox hardware.)
Another part of the lost air level.
This is the great tree with a different sky cube from December, 2000.
Here is the top of the air realm under development, from December, 2000. Notice the temporary staff effect for lightning.