I thought Parallels was all right.
A simple concept for a puzzle platformer that I might want to see again in a future installment, but as it is now, I found it too difficult. Movement is very fast and tight, which normally would be great, but when I you're contolling two characters at once, it feels like I don't have enough time to glance over at what the other one is doing.
Most of my complaints could be fixed with the addition of sound/music, and perhaps a button to switch the focus of your character so that the bottom avatar's controls become uninverted for when I need to focus on what they're doing. and vice versa. In my short time with it, I just never got used to that.