So you guys are talking about "general" game technology.
I asked about graphics technology...but thanks for the answers!
Fully dynamic and realtime shadows, 24h dynamic lighting, POM for certain effects (car tire marks and some forms of deformation, bullet holes), millions and millions of polygons to render city with huge amount of dynamic and static objects, advanced animation system, lots of characters and cars with advacned properties, lots of soft particle in effects with sparks that bounces on everything (terrain, static, dynamic), 3D deformable water with realtime reflections and refractions, 100's of dynamic lightsources, working city system that brings life to it, cars reflecting surrounding and not just a singel car doing it, some building windows reflecting city in realtime, at night tons of moving lights to simulate cars at distance and much more.