Got all the badges. It's pretty hard, but once you get used to the mechanics, it's not that bad. You have to use the variable jump length to your advantage on Infinite mode to beat some of the levels, and if something's just too hard, randomize it.
The biggest problem is not multitasking, it's bad placement of the games. I keep accidentally using A and D to adjust the balancing one because it would make sense that I'd be controlling the game on the left with my left hand. It keeps screwing me up at around 70...
A nice bug - if you buy the healing spell for someone, choose cast magic, choose the healing spell, then cancel, you can have any of your characters take a turn, even if they've used their turn already. Combine that with someone with a great weapon, and it becomes quite simple.
It's not giving me the badges even though I'm doing everything... I got first in a race, and I didn't get the badge. I've got over 20 in-game achievements, and I didn't get the challenge...
Unbelieveably bad game. The AI is abysmal - they can see you off the screen, something that an AI shouldn't be able to do. Second, the collision code is awful - there were many times that my grenades went straight through enemies without exploding. 2/5 for effort.
 "Shoot Pixels"){kind=icon}
 "Solipskier"){kind=icon}
 "SkyFyre"){kind=icon}
 "Run"){kind=icon}
 "Multitask"){kind=icon}
 "Turn Based Battle!"){kind=icon}
 "CycloManiacs"){kind=icon}
 "SHIFT 4"){kind=icon}
 "Smileys-War"){kind=icon}