game-loader.jsx

class LoaderWithGame extends React.Component {
  state = { isPlaying: false }

  startGame = () => this.setState({ isPlaying: true })

  endGame = () => this.setState({ isPlaying: false })

  render() {
    return (
      <React.Timeout>
        {didTimeout => (
          <React.Fragment>
            {(didTimeout || this.state.isPlaying) && (
              <LoadingGame
                onStart={this.startGame}
                onEnd={this.endGame}
              />
            )}
            {!didTimeout && <MainContent />}
          </React.Fragment>
        )}
      </React.Timeout>
    )
  }
}