This page describes a bug in RollerCoaster Tycoon 2 (RCT2) that I stumbled across that I'm calling the "scribble" bug. I think the reason for the name will eventually become clear as you read this. I don't know if I'm the first person to run across this bug -- probably not -- but I haven't seen it described anywhere yet. So here goes...
I was experimenting a bit with a well known and well publicized bug in RCT2 (for example, read this) that makes it easy to generate some extra cash. Well, it gets tedious laying down lots and lots of scenery. So I thought I'd try saving a custom ride with the scenery attached to it. Then I could just plunk down the ride and instant scenery; delete the ride, build a ride atop the scenery, and then delete that second ride and instant cash.
The custom ride I saved was a launched freefall. Rather than have the scenery next to the ride, I decided to put the scenery under the ride. So the saved track file has a 3x3 layout of base blocks, 16 blocks high (the size of a 3D Cinema). However, it was a failure -- when you go to build it, the ride is build at ground level and the blocks underneath it are never built. If you want to see for yourself (and in a moment you will want to), go ahead and download my track file and put it in your "Tracks" folder with all your other RCT2 *.TD6 files.
Now that you have the track, try building it. See anything odd? Well, when I tried building it in the Ghost Town or Build Your Own Six Flags scenarios, it left behind a white "ghost" of the base blocks. Experimentation shows that the ghost is only left behind on flat land. And if you move the ghosted ride around a bit, then it leaves behind a ghostly trail. In fact, you can scribble all over the landscape, using the ride as if it were a paintbrush. (See why I call it the scribble bug?) You probably want to see what I'm talking about, so here's a screen shot (click the image to see it full size):
Well, so far it's just a curiosity. But this is where it gets interesting. You see, that white ghost isn't just a drawing artifact. The game actually thinks something is there. If you move the ghost off screen and then go back, it's still there. But if you build on it, it's not like scenery. It stays there, and when you delete the ride, the ghost remains. I've only found one way to get rid of it, and that is to use the scenery deletion tool (the bulldozer icon). That will do it. And, even better, when you delete the ghost, you get cash back! Look at that screenshot again -- I never once actually placed the ride. I just dragged it around, closed the window, and deleted the ghost.
And just look at the cash I racked up doing it! I've found that it's pretty easy to rack up over $400,000 in about 2 game months. Unlike the scenery deletion bug Fossil describes, this one doesn't even require an initial outlay of cash. Not a single penny. The money only flows one way: into your piggy bank. That's not too shabby!
I noticed another thing, too, as I played with this. If you scribble a lot over the same area on the map, it's like the ghost accumulates or builds up. When you delete it, it's worth more cash! So scribble lots, and make more money even faster.
But it's not all good. I think that there might be an internal limit on how many scenery items can rest upon a given square on the game's grid. And normally, scenery takes up actual space, so you can't ever put too much on a square. Thus, the programmer (Chris Sawyer) figured, since it can never happen, I don't need to check to see if there's too much scenery. Ah, but Chris, you were wrong! This ghost seems to behave like scenery, and the game stores it in the internal data structures, BUT it also seems to have zero height. So you could in theory collect an infinite amount of it...and the game doesn't like that. If you scribble too much in the same spot, the game crashes with the dreaded error trapper. So, the moral is this: you can make lots of cash fast by exploiting this bug, but don't overdo it, or you'll be sorry! And, just in case, save often -- you are figuratively playing with fire!
I haven't tested every scenario to see if this bug appears everywhere. It definitely only appears on flat ground, so don't even bother with this in hilly scenarios. And if you zoom way far out, as you scribble you'll see a temporary ghost flicker in and out at the highest height in the game. I have a suspicion that the blocks that aren't being built -- which by all rights should be appearing underground, are "wrapping around" in the internal data structure and coming out up at the top. So it may be that only areas where the blocks under the saved ride track are taller than the distance between the ground and the bottom of the map will exhibit this bug. I haven't tested that yet...but all the places I've been able to use this bug have had the ground such that at least four of the blocks would be lower than the absolute bottom of the game map's volume.
And that's it -- the scribble bug. Happy cashing-in time!