What makes you guys think there is ambient occlusion on that house? To me, it looks like a somewhat highpoly model with normalmapping and specularity.

btw, 'soft shadows' is not really an accurate description. Soft shadows can come from lightmapping, shadowmapping or shadow volumes. I guess (but can't be sure) they used a global shadowmapping shader.

I think the athmosphere of this game is caused mainly by the colors and style they used.

EDIT: after looking at those last screenshots (wheren't there when I posted), I can say it looks like shadowmapping with percentage-closer filtering.

We aren't really missing anything in gamestudio, you just have to write those shaders.. You might say "yes but an engine should provide shaders X and Y". In reality, however, you will need a different shader for almost all models. Using 'uber shaders', like the recently released normalmapping shader is a bad idea because it does many more things than you need, slowing it down. If you want to create a scene like that, you will have to do shader programming anyways, and all those shaders are freely available on the web, you'll just have to edit them to work with gamestudio and suit your specific needs.