You could write a plug, which calls put_layout on the conn depending on the roles of the user stored on the conn.

put_layout is the right way to deal with custom templates for certain roles, but I think what you are asking for is how to redirect the user after sign in depending on the role.

You can customize the callback routes to redirect admin users: https://hexdocs.pm/pow/1.0.13/README.html#callback-routes

So you can do something like:

defmodule MyAppWeb.Pow.Routes do
  use Pow.Phoenix.Routes
  alias MyAppWeb.Router.Helpers, as: Routes

  def after_sign_in_path(conn) do
    user = Pow.Plug.current_user(conn)

    case user.role do
      "admin" -> Routes.admin_dashboard_path(conn, :index)
      _any    -> Routes.game_path(conn, :index)
  end
end

This will redirect admin users to the admin dashboard instead of the game page. Remember to add routes_backend: MyAppWeb.Pow.Routes to the config.