In 2011, Rideau and Winskel introduced concurrent games on event structures, generalizing prior work on causal formulations for games. In this paper we give a detailed, self-contained and slightly updated account of the results of Rideau and Winskel: a notion of pre-strategies playing on event structures and a characterisation of those (called strategies) which are preserved by composition with a copycat strategy, and the construction of a bicategory of these strategies. Furthermore, we prove that the corresponding category has a compact closed structure, and hence forms the basis for the semantics of concurrent higher-order computation.