Nice, simple game concept - but works a treat... REALLY nicely presented and clean art style - very polished!
I did find playing was a bit laborious, some of the objects felt too far to reach in time. It all felt too low too, it would've been good if they bounced up so they were closer to the eye-line.
As Toreador suggested, using hand would've been a good addition too (I know it's probably a time thing for the Jam) but perhaps a shield in one hand and a sucker gun for collecting gems might be cool. Just to add more variation to it.
Overall, very well presented game and really cool idea - I enjoyed playing it!