Games which not only attempt to accurately represent the environment but also the users/vehicles interaction with it. The interaction components are an integral part of the game and are stressed over the action aspects in order to represent the environment better. Another key characteristic is that gameplay and controls are often much more complex than in action games.
Accumulate wealth at the expense of others' suffering by picking up patients with your ambulance in this 3D driving fantasy for Windows. [Open Source, GPL] http://critical-care.sourceforge.net/
An animated cat that sits on your Windows desktop, chases the mouse pointer until he catches it, and performs other kitty activities. (Open Source) http://www.angelfire.com/ct/neko/
