Cyanide is a MMORPG (Massively Multiplayer Online Role-Playing Game) or graphical MOO (Multi-User Object-Oriented). It was an effort to bring the flexibility of MOOs like LambdaMOO to the graphical user. But it failed, since the project had not enough graphics, not enough users and its goals in the end differed too much from the goals in the beginning.

But Cyanide can nevertheless be downloaded and played. See the SourceForce project page.

LambdaMOO has a very exciting scripting language to power its objects. It is similar to C, but is object oriented and you can define access rights (read/write) for every property and method. It does not differentiate between class and instance. If you create a new object, you specify the parent object and get a subclass (or subobject) of it. If you do not change anything, the new object should be identical to its parent. But you can replace any property and method by your version. And the best thing: You can make any change to the objects or their code while the MOO is running.