when i was online i believe there were in excess of 1100 others also playing the games, and taking in the educational materials [mind you that was near the 1 am eastern server down time]
In fact, I was invited back for the polar bears party on the weekend.
Enviromental education appears to be at the forefront of this work from the nice people at Good Egg studios Inc.
it is NOT a CITC product, but is expected to be found within thechildrensinternet
You can indeed register for free, some in game premium options require a membership the prices are very reasonable but are not requred to register or connect,