Well damn. I should have looked at this forum topic before having a go myself
PRESS F6 TO GET YOUR AFTERNOON BACK
A few notes about my version of the game
I found an infinite lives hex-edit guide, but it seems to be for a different version of the executable.
No oversteering issues until I took the clocks very high. I suspect the game was designed to run comfortably at a low framerate, something we are not used to thinking is normal.
My version only came with one map: Pacific Yosemite
Initial analysis
The level appeared to be segmented into square regions, ala chunks in Minecraft, and you can trace the seams across the entire map. Setting the quality to low makes this more obvious as adjacent chunks tend to stay hidden for longer.
It appeared like the terrain was a height-map and the roads + entities were added ontop.
I took the file-analysis approach rather than analysing running memory. Some rudimentary DOSBOX debugging and flower-arrangement lead me to believe the map data was stored in SCENE01.DAT
File analysis
Method:
1. Blank out a segment
2. Load the game
3. Observe what happens
This data file is amazingly resilient. I'm convinced a lot of what's in there is unnecessary
Results
Around 0x7600 in SCENE01.DAT appears to be the heightmap values for a chunk directly infront of the starting position (just before the bridge). They look like two-byte values and appear to start with the north-most row (assuming you start the game facing north) going left to right. This particular chunk is mostly the same (00 02) for all verts as it's flat.
I could be horribly off-track as I only dabbled into this over the last few hours. To find that someone had already completed is downright crazy -- consider yourself admired ripa!
Other interesting things I discovered
Some patches of brown land near water are marked as 'road' by the game.
Some interesting error messages: see attached
The road and entities are indeed sep data to the terrain. I suspect the road is rendered after the terrain to ensure the correct Z-order. Cars follow the road blindly, even through terrain.
Changing 0x766a (X) leads to some very fun corruption of the chunk I was playing with. It's probably a start/end marker or counter for a number of some element in the chunk. It let me 'finish' the race by driving through the chunk (beat my best time of a few seconds!).
