Special Level
Find all GTA 2 Shields and you can play the 3.Special Level.
Guided Tour
Go to the phone at the beginning of the first level. A "Schmidt" car will appear below. Enter it and wait for instructions. After finishing the tour, a machine gun and a GTA2 sign will appear below the church.
Wang Cars Bonus
Get all eight Wang cars to get a fire truck that shoots both fire and water; 4 Furor GTs (one with 50 machine guns, two with 50 mines and one with 50 oil slicks), a tank with 20 rockets, a special agent car with 50 machine guns, and an armed land roamer with 20 military machine gun rounds.
...