Statestep is unique - but that doesn't mean it's necessarily relevant to the problem you want to solve now. If it isn't, you may find some of the following links helpful. Note: no endorsement of other products is implied by their being linked here, and no responsibility is accepted for the content of other websites.
Link Compilations: Methods, Requirements Engineering
Ian Alexander maintains a comprehensive annotated list of general requirements engineering tools.
The Formal Methods Wiki aims to cover many formal methods of specification.
Tools For Rules
Drools is a rule engine designed to apply a repository of stored business rules (for example, "credit is never extended to a new customer without the approval of a manager") to a large database of facts.
OpenRules also positions itself as a "Business Rules Management System". A decision table tool framework aimed at web application development allows tables for logic and presentation to be entered in Excel spreadsheets.
Prologa is a decision table tool that allows rules to be expressed in an AI / fuzzy-logic style ("Generally, do Action Z if Condition X and Condition Y") and supports multiple, connected decision tables. Commercial, MS Windows only.Questions, comments? firstname.lastname@example.org