At the moment it is more or less a FPS game maker. However it has potential to be used for RPG's, Adventures, Survival games. Later on 3rd Person, RTS and other totally different game types are planned. For now though the best you can do is an adventure or RPG or a basic shooter of course. You also need to be able to script in Lua, to do either adventure or RPG. There's not too much out the box that will help as yet.
Check out my Project RPG stuff. The scripts are currently in the hands of TGC testers and are awaiting approval. So that would be a start for an RPG game for instance. There is also a few useful scripts I have done for general gameplay mechanics not supported as standard. There's also a lot of free scripts around for all sorts. It all depends how easy you want to make it for yourself really. That is one of the good points about Game Guru you can concentrate on the game design and leave the more difficult modeling and scripting for others to do and buy them
or have a dabble in all, whatever is your preference!
All the things you mention are possible, but not out the box. As is I wouldn't think player controlled vehicles would be possible yet, or at least in a realistic fashion. I wouldn't want to try it, particularly at the moment. Helicopters and such flying around though is no problem at all.
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.