Agreed on suitable games for this - I would think it's more suited to sandbox 3d stuff like Garry's Mod.
I fancy dabbling with the dev kit - for those of you using this with Unity, can you use it with the free version? From what I've read you need the pro license to use plugins - and $1500 seems a lot, just for me to play around.
You can just, umm... "acquire" the pro version, and then pay for a proper licence if you plan to release something using it. That's what a lot of people (individuals, not game studios ) I know have been doing, as for an individual it's pretty steep if you're not even sure you're going to release something with it.