Compositional game theory concerns open games, which are building blocks from which games can be built in a compositional way. At first glance (and at first in the historical development of the topic) this has nothing to do with bx, but a certain notion of lens has turned out to be central to the study of open games. The goal of this talk is to introduce open games to the bx community, and discuss some ways in which the theory of lenses is proving useful to compositional game theory.