Dynamic epistemic logic (DEL) is a popular framework for studying interaction in multi-agent systems. DELs describe the actions available to the agents, and their epistemic preand post-conditions. By extending standard epistemic models with preferences over epistemic states, we can say something about rational behaviour as well, combining logic and game theory. In this paper we assume that preferences are represented by epistemic goal formulae, and actions are public announcements as described by public announcement logic. We are interested in analysing coalition formation and in particular coalitional stability in such settings. To this end, we describe how such epistemic goal models can be viewed as coalitional (cooperative) games, and study and characterise the resulting class of games and their solutions in different ways. We use a model of coalitional games under imperfect information that is more natural for many logical and computational settings than most existing models, and propose some related solution concepts extending the notion of the core under common knowledge.