Platypus

Platypus is an alternative to the standard Inform library, developed by Anson Turner.

The current version is 4+.

Features of Platypus, beyond those of the standard library, on which it is based:

A finer grained system for handling actions, which includes function properties for catching actions on indirect objects in place of the "fake actions" used by standard Inform.
Darkness is handled in a more logical fashion than in the standard Inform library; there isn't a "thedark" pseudolocation.
It includes support for having NPCs perform actions.
Its parser contains support for adjectives.
Objects may be any combination of supporters, containers, and "hiders" (objects that can have other objects underneath.)
Some global entry point routines have per object property equivalents.
There is support for pathfinding between rooms on the map.
The system of "gizmos" and "cogs" allows a programmer to make changes to scope or to default messages by moving cog objects into and out of the appropriate gizmo object.