This is why I´ve written "next gen" in quotation marks.

" If you want to make a small little simulator (like you mentioned)"

Small little is relative.
The "Landwirtschaftssimulator" (farmer simulator) for example is completely modable, over 250 mb heavy, has its own engine
( http://gdn.giants.ch/ ), a special foliage system, missions, physics, day/night cycles, a weathersystem, a lot of different vehicles and tools, a leveleditor...

This was a rather big project for an indie.
Same goes for all the other simulations.
I was very surprised about the amount of work that goes into
such projects.

@ the Lord:
"I have visions too, but i wont release them here for fear of theft!"
Are you serious about that? (I think you´re not)