This has to be one of the most difficult games I've played. Finally finished it in hard mode (I never play games in medium or easy)
It has a very unique look, since absolutely everything is hand modeled in clay. When I mean everything, I mean models, special effects, even the text and numbers.
It's gorgeous
Well worth acquiring the full version.
Here are some screenies



Retro64 has some other fantastic games, including zball and bugatron (they didn't make platypus from scratch though, I think they bought it from another company and refined it)