I've been grinding away at M999 Game lately, trying to unlock Britton. It's a bit of a process, but it's definitely worth it. I've found that the key is to tackle the "Easy Missions" folder one by one. It's not as straightforward as just skipping ahead or expecting background grinding to clear multiple stages at once
register. But hey, that's the beauty of this free mobile game, right? The final touch is that you must complete these missions sequentially to unlock Britton as efficiently as possible in M999 Game.