flame/doc/examples/go_desktop/lib/main_desktop.dart

import 'package:flutter/foundation.dart'
    show debugDefaultTargetPlatformOverride;

import 'package:flutter/material.dart';

import './game.dart';

void main() {
  debugDefaultTargetPlatformOverride = TargetPlatform.fuchsia;
  runApp(MyGame().widget);
}