Out of curiosity, I dropped in on ActiveWorlds this morning to see what it was like. As Eggy put it, "it's SL's grandpa". It's a 3D world with chat, like SL, but the feel of it is like a computer game from ten years ago. Avatars are stiff and lifeless, chat is IRC-style in a separate window pane, and I can't tell if there's a physics engine. But it's all there -- user-made content, socialization, and a gigantic world with lots of places.

Naturally, the first place I visited was an airport.



(When I switched from the default first-person camera to the third-person camera, I was a little surprised to discover that I'd turned into a fish!)

As Eggy pointed out in-world, the models are mesh-based, so they have shapes that may not be possible in Second Life, where building is primitive-based. Look, no seams!



Not all planes looked expertly-made, but that's the same in SL, where all content is created by users -- everyone has different skill levels, but everyone contributes. Some of the planes would do very well if they were built and scripted in SL.

I can see why ActiveWorlds lasted so long. It must have been cutting-edge in the beginning, and even now it offers much of the same experience and community as SL... but without the lag.