I tried playing it with one other person the other day and even after watching the tutorial it was kinda slow and confusing. :C Is it supposed to be like Balloon Battle in Mario Kart or something?
Actually you just go around and get items to make your machine OP, and then you play the minigame afterwards, whoever wins the minigame wins that round. It could've been fleshed out a lot more. But for it's simplicity it's still amazing. Plus there is lots to do, you can find secrets, kill each other, fly around the city, lots of stuff. I do recommend playing with 4 players at all time. More CPUs at the highest difficulty if less than 4.