Ambient Events in GTA 1 Coding
Getting missions from payphones, doing kill frenzies and generally causing mayhem around the city starts to lose its appeal after a while. A long while but nonetheless, a greater variety of tasks would improve GTA 1 a lot. I was brainstorming other things the player could do and realised that the GOURANGA bonus was something which was always fun but wasn't actually a mission.
Maybe the mission code could be made to also do things which could be fun without being formal missions?
Devising Ambient Events
After studying the original missions more carefully and playing the cities, I noticed there are other things which are fun but which are not formal missions. The Random Pager messages are created using the mission code, as are the gangs of thugs in the Vice City chapters, as are the Insane Stunts. I wanted to develop something original which would be fun to do and could be done over and over again with slight variations.
What I found was that the GTA 1 mission scripts do not allow the respawning of coded vehicles but you can load the data from the vehicle the player is currently in, even if it was created by the map. This means that by using citizen vehicles you could theoretically redo missions so long as you took the car into a garage where it could be destroyed, allowing a new car to be loaded. The DUMMY object used to store vehicles cannot respawn, so previous vehicles would have to be destroyed.
Another discovery was that when you are told to take a number of cars of a certain type to a crane at the docks, that car never gets loaded into a DUMMY and so these are a truelly re-usable type of mission.
The End Product
I implemented some of these ideas into my Uphold the Law level. When you enter a Tanker truck you get a delivery mission, if you enter certain types of sports car you have to deliver a series of them to a crane. If you enter a Monster Bug then you get a kill frenzy. At the end of each mission the car is destroyed by driving it in a garage or the rather more brutal timed carbomb approach. However, if you find another edition of the car driving around the city you can get in and do the mission - or the kill frenzy - all over again!
Some of the missions actually have a few variants, so you deliver the tanker trucks to different locations. Different sports cars are wanted by different cranes. Also, the kill frenzies require more points to be completed each time you suceed.