Experimental Penguins was a game released in the year 2000. It was a multiplayer game/chat, similar to Club Penguin and Penguin Chat 3, and it was made around the time of Rocketsnail Games. Experimental Penguins was the original Penguin Chat.
Players would join as a normal, blue penguin, while in a different edition of Experimental Penguins, you would be able to wear a santa hat. Developers would get a Snow Trekker to roam around the island (the players would also get it by touching the North Pole in the game).
Experimental Penguins stayed up for less than a year, but it got several awards. It closed down in December 2000, and then Penguin Chat was released a few years later.
Ballistic Biscuit reference
In February 2001, in the game Ballistic Biscuit (now known as Hydro Hopper in Club Penguin) a blue penguin from Experimental Penguins could be seen in the boat during gameplay.