You can smash things and get away with it. Smashing things doesn't hurt. Many nice things are hidden inside other things. When someone dies, they disappear. Money is frequently found lying on the streets.
All shopkeepers carry high-tech weaponry.
You never run out of bullets, only grenades. Ninjas are common, and fight in public frequently. Whenever huge evil fat men are about to die, they begin flashing red or yellow. When you are born, you're invulnerable for a brief period of time. Although the enemy always has more aircraft than you, they fly in predictable patterns which makes it easier for you to shoot them all down.