The SYS.PAK file, located under SimCity 3000 Unlimited/Apps/Sys/, is an archive that contains a myriad of uncompressed game configuration files. While some files contain mostly hexadecimal mappings and generally undecipherable information, quite a few of them include readable and interesting game parameters that are fairly easy to view and modify. Some of the things you can do include:
Alter area-of-effect stats from buildings, including crime, pollution, and land value generation
Change the plop costs, capacities, and general life expectancy rates of utility buildings
For my example here, I've modified the effective lifespan of the fusion power plant. Always thought it was a little odd that the most expensive and futuristic plant (by far) is hampered by the shortest overall lifespan. Also, comic sans? Really?
OPENING THE ARCHIVE
Please ensure that you create a backup of SYS.PAK, in the event that you repack the files and the game no longer functions.
To extract SYS.PAK, you will need to download SC3KPAK (windows only). Place the SC3KPAK.exe and Sc3kpak.lng (thanks @CorinaMarie) in the Apps/Sys/ folder and run command prompt. cd to the working directory of SC3KPAK and run the following command:
sc3kpak e sys.pak
This will extract the contents of the archive to the current working directory.
Now you're ready to begin the editing process! Open any of the .ini files in your favorite text editor and begin tweaking some values!
I'll try to update this post periodically once I've perused the files a bit more.
SC3ComLayer, SC3IndLayer, SC3ResLayer: These files seem to define certain constraints for the RCI model. The ResLayer is significantly more comprehensive.
InitialConnectionSupply - This looks to be the initial maximum commercial and industrial capacities, without any cap relievers. Default is 25,000 and 70,000 respectively. ExternalFunSupply - seems to be the same thing for residential, sitting at a default value of 25,000.
SC3Tune: Controls parameters for several different portions of the simulation. Also contains stat values for a lot of the civic buildings, garbage disposal and the water treatment plant.
MaxDistFromTransport - Indicates the maximum tile gap from a transportation network tile (road, subway, rail, etc.) a zone will develop. Defaults are 2 for commercial, 3 for residential and 4 for industrial. I'd imagine setting this value to something like 255 would result in some super clownly development.
[Higher/Lower][LandValue/Density]RedevelopmentPct - Sets bias for the simulation's redevelopment of areas. Default is a even split for residential and commerical and a 30/10/30 split for industry. Modifying the percents here would help skew development to favor a certain type over others I'd imagine.
SC3LandValue: This SC3000 knowledge tree article does a very good job outlining practically everything found in this file. You have control over the city center, elevation, water, building and ordinance effects on citywide land value.
[Res/Com/Ind]CityCenterEffect - This is the city center effect bonus described in the plots from the above link. The initial values in each section is displayed as 45+80 for residential, 45+60 for commerical and 10+100 for industrial. The value left of the plus sign is the base land value, while the right value denotes the percentage of the map from the center where you'll get the bonus land value. As you develop your city you may find your geographical city center constantly shifting. If you've ever experienced having your commercial zones fade out in land value as your city grows, the shifting city center combined with the limited 60% bonus radius is the culprit.
The AgentIDModifiers section describes the individual building effects on land value.
Yes, by changing that -90:R to 100:R, you can make it so that your rich sims won't mind if their nice mansions are right next to that disgusting coal power plant. You can go even further by changing the AirPolluteFactor and GarbagePolluteFactors to positive numbers for a positively silly result.
Similar files to this one include SC3Pollution, SC3Aura, SC3Crime. You can also control how frequently these data layers update in-game by changing the UpdatePeriod parameters
SC3DisasterLayer: Controls parameters associated with disasters and the parade. Looks like a fun way to cause some extra chaos!
SC3BudgetLayer: Controls budget items, which includes plop costs, tax income and loans.
LVTo[Res/Com/Ind]TaxTransmogrifier - From my understanding, this is a multiplier applied to the land value of the particular RCI tile. The product of that formula is the tax revenue you earn. Naturally, the higher this value, the higher the amount of money you earn from taxes. Default values are 35 for residential, 45 for commercial and 50 for industrial.
A city of 465,000 people that was earning approximately 62,000 simoleans a year was now slated to earn 216,000 after doubling each respective value.
SC3PowerLayer: Controls most power utility statistics, including lifespan and capacity. [Min/Max]OverworkMonths - Range in which an overburdened power plant can prematurely explode. MaxLifeSpan - 12x the maximum number of years a power plant can operate before it explodes. (ex: value of 1200 = 100 years) DeclineAge - 12x the year when the power plant starts operating at less than 100% capacity. (ex: value of 768 = plant starts aging at 64 years) PercentageVariationInLongevity - randomizes the maximum lifespan of the building within this percentage of its MaxLifeSpan. In essence, it turns MaxLifeSpan into an average (15% longevity at 1200 = 85 - 115 years)
SC3WaterLayer: Controls most water utility statistics, including lifespan, capacity and consumption (no treatment plant). Interesting properties:
WaterFromPipe - The maximum amount of tiles from a pipe that water will reach. Default is 7. DefaultLeak - Seems unused. My theory is that the aging water pumps were supposed to 'leak' and cause something bad to happen. Rather, aging functions much like power and garbage utilities with gradual capacity decrease over time.
Another interesting tidbit I noticed is that several files contain a reference to a 'Launch Arcology' building. I'm guessing this was supposed to be a reward building in a similar vein to the arcologies of SC2K but was ultimately cut from the game.
PUTTING IT BACK TOGETHER
Once you're done editing, open the command prompt back up. In your current working directory, type:
This will automatically package the configuration files into a new SYS.PAK. If you're working with the archive in a separate folder from the Apps/Sys/ folder, simply copy your new SYS.PAK back into there. Otherwise, start the game and see the fruits of your labor!