Home sick today, and as I was clearing out old files I found an old version of Unity, a game-design program. As with Daz 3D and Bryce Unity now has a free license; it's less functional than the full version, but it lets you do some interesting things (with a big learning curve involving scripting), the idea being that you might also want to buy content from their online store.
It ships with a playable and exportable shooting game - you can turn it into an .exe or .app - so you can get a look at how things are built, which is kind of fun. Other than that game and other demos you can find elsewhere you have to import stuff into it to use it (it'll take various kinds of 3D objects and images and sounds from every other program I mention in this post). Figuring out how to wrap 3D objects is not something I have a handle on, so maybe I'll learn. I think I may try to have my little shooting guy in the provided game have a Santorum Gun. Runs on Macs and Windows, and compared to Daz (character models) and Bryce (environments) it's a comparatively zippy little program on my underpowered second-hand machines. The interface is good compared to the other programs, although "better than Blender" is not really that much of an endorsement. Still, the documentation is clear and the process of GETTING the thing was easy in comparison to the weirdness of trying to get Bryce and Daz.