Towards a unified metamodel for i*

i* is a framework for goal-oriented requirements modeling. This framework contains an organizational modeling language defined by actors and dependencies among them. Although i* has been widely used, it is still hard to work with it due to its diversity of variants. In this paper, we propose a unified metamodel that presents elements of two well-known variants of i*. We show how OCL restrictions can be applied this metamodel in order to generate a specific variant. In doing so, we intend to unify the efforts of i* community. This metamodel can be useful when developing generic tools for i*, as well as to reason about i* language. Moreover, it makes it easier to extend the i* language. Thus, our proposal is an attempt towards the unification on i* variants by considering similarities and differences among them.