Sounds like a groovy idea, but we already have a working arcade going on right now. I might edit this post with a link. As for the highscores, I think we can manage a system like that.
But, here's my idea: instead of everyone turning this into some slaughterfest to see who will rise above the other, we can possibly make a separate section/thread for people to post their high scores on.
Say, for instance, I got an epic score in a game and I want to show it off to some friends. I'll make a thread in a possible High Scores section and then we can show it off there. I'd also post a screenshot or off-screen photo for proof. Then, someone else will go to that thread and post his high score.
We could also have Stats to see who has the highest score in a specific genre or game.
We could seriously pull this off, unless people say otherwise. I'll be willing to kick it off, too.