I used to play this game for hours! My favorite things to were to trip NPCs by selecting them and just tapping the pk button. The AIs were programmed to look at the "floating person" so when they "tripped" they all looked at them like "WTF is wrong with that guy?" The other thing, which could only be feasible later in the game was to grab a vehicle/large flat object and smash the NPC "into" the ground, causing their rag-doll to start clipping into the ground making the model's bones stuck between the floor. They could take quite a few hits so if you did it right, they might be left with 50% or more of their health. When they attempt to get up, the model violently starts shaking causing micro-collisions to the NPC which slowly drained their health. If they were lucky, they would blip to being in the standing position, skipping the animation. If not, they either lost all their health, or slipped into the floor fully (if shoved too deep). Frankly, there wasn't much to do when the game was done. Sometimes I would go to China to see how many ninjas I could push into the city.
Sadly, these got written out in the remake. you can't tap-grab people, let alone be able to even drop them easily. Grabbing anything makes it hover a set distance from you so you become noticed whenever grabbing things... Before, "tripping" might have caused police to search around. Now, they notice right away and give chase.