I think the most fun and behinner-approachable way to build games with functional programming is with Elm [1].

See a few (small, demo) games built by the community in [2] .

Notice Elm has abandoned the FRP approach in favor of Model-View-Update [3].

[1] https://elm-lang.org/ [2] https://github.com/rofrol/elm-games [3] https://elm-lang.org/news/farewell-to-frp