P.A.W.S.
From IFWiki
The Python Adventure Writing System, or "P.A.W.S." (or even "PAWS") is a set of libraries, written by Roger Plowman, to allow one to reasonably easily write interactive fiction using the Python programming language. There are two versions of P.A.W.S.; P.A.W.S. 1.5, last updated in 2007, and the almost completely backwards compatible P.A.W.S. 2.0.
The download (both the development and runtime library) is a freeware download.