Study for “SimCity Four” on YouTube, and likewise you’ll gape players organising multilevel twin carriageway interchanges and intricate railroad networks, or even even a swooping flyby of a sprawling metropolis. None of those aspects came with the contemporary game, which was released appropriate after the turn of the millennium. They’ve been developed slowly and painstakingly over the 22 years since its release by dedicated aficionados — a thriving neighborhood that continues to push the game’s limits.
The work is a labor of esteem, and it’s rather a great deal of labor and esteem. Modder Tarkus says that after all these years, he’s drawn to the deep and complex nature of the game’s simulation, which he says remains unmatched by more fresh games luxuriate in Cities: Skylines (2015) and its sequel Cities: Skylines 2 (2023) — and even by SimCity Four’s have sequel, which was released in 2013 and easily called SimCity. Modder Ulisse Wolf says that, for him, it’s indirectly a request of neighborhood. Perhaps thanks to the game’s age, he finds that SimCity Four fanatics are “more ragged … guaranteeing you a aloof utter to reside in [peace] with diverse contributors.”
SimCity Four was released in 2003, the fourth in game company Maxis’ sequence of city-constructing games. It was moderately a hit, garnering certain reports and selling successfully ample for Maxis to release an growth pack later that twelve months. The means for players to add their have pronounce material to the game was a key share of SimCity Four’s charm from the open up: it came with a utter of instruments that allowed players to diagram and add their have constructions to their cities. Avid gamers soon began sharing their creations online by process of exchanges hosted on fan websites luxuriate in Simtropolis and SC4 Devotion (now defunct, but relaunched no longer too long ago as SC4 Evermore), besides to discussing guidelines and solutions in the accompanying forums.
“It grew to was certain to me that if I desired to gape more happen on the transportation modding front, I needed to be taught to carry out things for myself.”
Avid gamers soon began to switch looking out previous the officially supported solutions of together with their have pronounce material to the game and wondering what else will most likely be accomplished. Could maybe well additionally the game’s road system be expanded? What about the railways? Early modding efforts had been made easier by the sort the game retail outlets its knowledge, which, as modder Matias93 explains, is in a database whose format was shared with outdated Maxis games. The database retail outlets knowledge about the game’s varied aspects: for a form of road, the database would occupy entries for all the pieces from which textures to level to on show cloak when the player placed the road all the sort down to how basic site traffic the simulation would enable it to lift.
The game’s constructed-in instruments supplied no approach to access this database, so the neighborhood developed its have — no easy assignment, as Matias93 explains: “[This] required the vogue of a veritable suite of instruments ready to decrypt hexadecimal symbols into legible databases, and to import and export multimedia files from and to them.”
As early modders began to search out their arrangement across the database, nonetheless, they began to search out entries for programs that weren’t in the game: aspects that had been both unfinished or never utilized. “SimCity Four exhibits certain indicators of having gotten much less pronounce material and expansions than its creators [intended]. While a majority of those aspects are nearly irremediably broken … many others had been barely at attain to be repurposed,” Matias93 says.
The utilize of the instruments they’d developed to tweak existing entries, modders had been ready to originate the rudiments of those unfinished aspects into totally new ones. One among the first such aspects to be repurposed was an unused road kind, it sounds as if intended to be a grime road for utilize in rural environments. SimCity Four comes with loads of sorts of roads for players to utter in their cities: suburban streets, two-lane roads, two-lane one-arrangement roads, four-lane avenues, and highways. Avid gamers soon chafed against the boundaries of the latter: there was no approach to originate a twin carriageway with a differ of lane widths, and connecting a twin carriageway to a road community required the utilization of surely one of loads of prebuilt interchanges. Avid gamers who desired to possess and originate their have interchanges, or assemble highways with a differ of widths, had been out of luck.
The invention of the unused grime road supposed that there was utter for one more road kind, and modders old it because the premise for what grew to was the “steady twin carriageway” mod, a more flexible and customizable different to the game’s constructed-in twin carriageway system. Speedily, players had a few twin carriageway widths to take from, besides to modular pieces they might fair utilize to originate their have custom interchanges.
Tarkus remembers coming across an early version of the mod in 2006: “I used to be totally floored. [Even though] it was an extremely little mod at the time, I might well well notify it had doable.” Right-lifestyles commitments took him far off from the game for a great deal of of that twelve months, and on his return, he came upon that vogue had stalled. “It grew to was certain to me that if I desired to gape more happen on the transportation modding front, I needed to be taught to carry out things for myself.”
This day, Tarkus is the lead developer on the Community Addon Mod (NAM), a sprawling kit that entails the RHW mod alongside with a extensive quantity of diverse transport-based pronounce material: pedestrian department retail outlets, a new railway system, roundabouts, canals, bridges, and underpasses, besides to a comprehensive reworking of the game’s site traffic simulator. The mod remains in active vogue — its forty ninth version was released in March 2025 — and is maintained and developed by a constantly transferring and evolving team, whose membership spans the globe.
Lucario Boricua, who spearheads vogue on loads of of the mod’s aspects, lives in Puerto Rico and is a civil engineer by day. He estimates that, as of early 2025, the team has around 25 fat-fledged contributors, alongside with diverse share-time contributors, playtesters, etc. The neighborhood is devoted on the total, too — contributors secure in every the long-operating forums and more fresh channels luxuriate in Discord, and every are on the total fantastic areas to utilize time, with ragged contributors welcoming new fans and what Wolf calls “political bullshit” critically absent.
It’s no longer appropriate the NAM that remains in active vogue, both. In 2025, SimCity Four modding continues to conform and embody new probabilities, largely thanks to improved access to the game’s supply code. Matias93 explains that “the first 15 years of modding, roughly, [had nothing] to carry out with coding per se.” As a replacement, they involved customizing and extending the game’s databases. Alternatively, that modified in the 2010s thanks to 2 key developments.
The principle was the release of a share of the game’s code, supplied by the uninteresting Paul Pedriana — the game’s customary chief programmer — in accordance with a put a question to from the neighborhood. This allowed for the reimplementation of some of the game’s inner debugging aspects, which were essentially cheat codes that allowed developers to carry out things luxuriate in fleet utter up cities without caring about practicalities luxuriate in having ample in-game cash, utter explicit constructions right this moment, and loads diverse handy aspects. Then, in 2019, a 64-bit macOS port of the game was released — with an unexpected bonus for modders. “Lots of the game code [was] legible on the released executable, allowing modders to establish certain that that you might well well maybe also imagine hooks to work with,” Matias93 says.
Modders proceed to lack fat access to the game’s code, but even little access has allowed the utilization of how that might well occupy in any other case been unimaginable. Predominant among these is the utilization of dynamic link libraries (DLLs), which enable custom code to be loaded into the game’s executable at runtime. The means to write down custom DLLs has allowed modders to repair long-standing bugs in the game — most critically, one infamous mutter that might well well lead to keep game corruption in natty cities. It also let them dream up aspects that don’t were that that you might well well maybe also imagine in any other case: most modern additions include a 3D camera, the reimplementation of the game’s long-broken water system, and a Steam Workshop-esque interface for discovering and downloading custom pronounce material.
Alternatively, the technique of growing these aspects remains far much less easy than for up to the moment games, which regularly come with dedicated vogue kits designed for modders’ utilize. So what’s it that retains the NAM team and its fellow modders engaged on SimCity Four, painstakingly implementing new aspects and testing the boundaries of what’s that that you might well well maybe also imagine?
Lucario Boricua says that engaged on the game at the brand new time feels luxuriate in “standing on the shoulders of giants.” The decades of work that modders occupy put into the game present a platform for at the brand new time’s creators to push the game into areas its designers potentially never imagined: “We’re centered on doing innovative things that redefine what’s that that you might well well maybe also imagine.”