Wanted to give my review of this since we've been playing with the demo all weekend. We love it! The free demo lets you do 18 levels - there are 70 total with the paid version which I hope to get for Mother's Day (it's more for me than for ds5). Also to compare with Fantastic Contraption, I like them both - they have the same basic goal: get the ball or wheel to the goal. You just use different tools and have different scenarios in each game. Fantastic Contraption gets more difficult faster so for ds5, he went through Crayon Physics demo rather quickly but with Fantastic Contraption, he got stuck a lot sooner and it was much more of a challenge sooner. This was certainly the case for dh and me also. If I could only have one, I would choose Crayon Physics. I just like being able to free-hand draw my contraptions. It is funny to view other people's designs on the Fantastic Contraptions (link under each level).
Another one to check out is:
http://linerider.com Very simple concept but there very elaborate designs on youtube that will amaze you.
As for drawing with the mouse with Crayon Physics, it's not bad with a touchpad mouse on my laptop. Even my dd2.5 likes to scribble with the onscreen crayon. I don't know how it would be with a traditional mouse though. I have problems with my hand using a mouse too much and causing pain so it would probably bother me. Coordination could be an issue too.
