Sight for “SimCity 4” on YouTube, and also you’ll gaze avid gamers setting up multilevel motorway interchanges and refined railroad networks, or even per chance a swooping flyby of a sprawling metropolis. None of these aspects came with the traditional sport, which modified into once launched appropriate after the flip of the millennium. They’ve been developed slowly and painstakingly over the 22 years since its free up by dedicated aficionados — a thriving neighborhood that continues to push the game’s limits.
The work is a labor of admire, and it’s somewhat about a labor and admire. Modder Tarkus says that finally these years, he’s drawn to the deep and intricate nature of the game’s simulation, which he says stays unmatched by newer games love Cities: Skylines (2015) and its sequel Cities: Skylines 2 (2023) — and even by SimCity 4’s enjoy sequel, which modified into once launched in 2013 and simply known as SimCity. Modder Ulisse Wolf says that, for him, it’s sooner or later a requirement neighborhood. Most likely as a consequence of the game’s age, he finds that SimCity 4 lovers are “more veteran … guaranteeing you a quiet deliver to are living in [peace] with other contributors.”
SimCity 4 modified into once launched in 2003, the fourth in sport firm Maxis’ series of city-building games. It modified into once fairly winning, garnering obvious opinions and selling nicely enough for Maxis to free up a variety pack later that yr. The ability for avid gamers so that you just can add their enjoy tell to the game modified into once a key share of SimCity 4’s enchantment from the beginning up: it came with a position of instruments that allowed avid gamers to make and add their enjoy buildings to their cities. Gamers soon started sharing their creations online through exchanges hosted on fan sites love Simtropolis and SC4 Devotion (now defunct, but relaunched no longer too prolonged ago as SC4 Evermore), as nicely as discussing tricks and ideas within the accompanying forums.
“It turned obvious to me that if I wished to gaze more happen on the transportation modding front, I wished to be taught tricks on how to pause issues for myself.”
Gamers soon began to examine previous the officially supported programs of adding their enjoy tell to the game and wondering what else could well be carried out. Would possibly well the game’s motorway design be expanded? What regarding the railways? Early modding efforts were made less complicated by the skill the game stores its data, which, as modder Matias93 explains, is in a database whose format modified into once shared with earlier Maxis games. The database stores data regarding the game’s various aspects: for a selection of motorway, the database would grasp entries for every part from which textures to reward on show cloak cloak when the participant placed the motorway all the model down to how necessary traffic the simulation would allow it to elevate.
The sport’s built-in instruments offered no skill to build up admission to this database, so the neighborhood developed its enjoy — no easy task, as Matias93 explains: “[This] required the pattern of a veritable suite of instruments in a location to decrypt hexadecimal symbols into legible databases, and to import and export multimedia files from and to them.”
As early modders began to hunt down their skill all over the database, nonetheless, they began to hunt down entries for systems that weren’t within the game: aspects that were either unfinished or below no circumstances utilized. “SimCity 4 reveals obvious signs of getting gotten much less tell and expansions than its creators [intended]. Whereas a majority of these aspects are almost irremediably damaged … many others were pretty at attain to be repurposed,” Matias93 says.
Utilizing the instruments they’d developed to tweak reward entries, modders were in a location to build up the rudiments of these unfinished aspects into fully fresh ones. One of the most first such aspects to be repurposed modified into once an unused motorway kind, it looks intended to be a dust motorway to be used in rural environments. SimCity 4 comes with various forms of roads for avid gamers to deliver in their cities: suburban streets, two-lane roads, two-lane one-skill roads, four-lane avenues, and highways. Gamers soon chafed in opposition to the boundaries of the latter: there modified into once no skill to build up a motorway with a broad selection of lane widths, and connecting a motorway to a motorway community required the exhaust of 1 in all various prebuilt interchanges. Gamers who wished to make and accumulate their enjoy interchanges, or manufacture highways with a broad selection of widths, were out of success.
The discovery of the unused dust motorway meant that there modified into once space for one more motorway kind, and modders used it because the postulate for what turned the “true motorway” mod, a more versatile and customizable alternative to the game’s built-in motorway design. , avid gamers had just a few motorway widths to employ from, as nicely as modular objects they’d well additionally exhaust to build up their enjoy custom interchanges.
Tarkus remembers coming all over an early model of the mod in 2006: “I modified into once absolutely floored. [Even though] it modified into once a seriously little mod on the time, I could well additionally picture it had potential.” Staunch-existence commitments took him some distance off from the game for most of that yr, and on his return, he figured out that pattern had stalled. “It turned obvious to me that if I wished to gaze more happen on the transportation modding front, I wished to be taught tricks on how to pause issues for myself.”
On the present time, Tarkus is the lead developer on the Network Addon Mod (NAM), a sprawling kit that entails the RHW mod alongside side an gigantic amount of other transport-primarily based totally tell: pedestrian shops, a brand fresh railway design, roundabouts, canals, bridges, and underpasses, as nicely as a comprehensive reworking of the game’s traffic simulator. The mod stays in energetic pattern — its forty ninth model modified into once launched in March 2025 — and is maintained and developed by a consistently shifting and evolving group, whose membership spans the globe.
Lucario Boricua, who spearheads pattern on various of the mod’s aspects, lives in Puerto Rico and is a civil engineer by day. He estimates that, as of early 2025, the group has round 25 full-fledged contributors, alongside side other share-time contributors, playtesters, and so forth. The neighborhood is appropriate on the entire, too — contributors accumulate in each and every the prolonged-working forums and newer channels love Discord, and each and every are on the entire effective areas to exhaust time, with aged contributors welcoming fresh followers and what Wolf calls “political bullshit” seriously absent.
It’s no longer appropriate the NAM that stays in energetic pattern, either. In 2025, SimCity 4 modding continues to conform and embody fresh probabilities, largely as a consequence of improved accumulate admission to to the game’s source code. Matias93 explains that “the first 15 years of modding, more or much less, [had nothing] to pause with coding per se.” As another, they concerned customizing and extending the game’s databases. Then over again, that modified within the 2010s as a consequence of 2 key trends.
The first modified into once the free up of a allotment of the game’s code, offered by the leisurely Paul Pedriana — the game’s normal chief programmer — in accordance to a request from the neighborhood. This allowed for the reimplementation of one of the most sport’s interior debugging aspects, which were surely cheat codes that allowed developers to pause issues love quickly position up cities without being concerned about practicalities love having enough in-sport cash, deliver particular buildings straight, and hundreds other precious aspects. Then, in 2019, a Sixty four-bit macOS port of the game modified into once launched — with an surprising bonus for modders. “Many of the game code [was] legible on the launched executable, allowing modders to establish particular imaginable hooks to work with,” Matias93 says.
Modders proceed to lack full accumulate admission to to the game’s code, but even little accumulate admission to has allowed the exhaust of ways in which would grasp in another case been very no longer going. Predominant among these is the exhaust of dynamic link libraries (DLLs), which allow custom code to be loaded into the game’s executable at runtime. The ability to write custom DLLs has allowed modders to fix prolonged-standing bugs within the game — most seriously, one notorious distress that could well additionally lead to place sport corruption in smartly-behaved cities. It additionally allow them to dream up aspects that have not got been imaginable in another case: fresh additions consist of a 3D digicam, the reimplementation of the game’s prolonged-damaged water design, and a Steam Workshop-esque interface for finding and downloading custom tell.
Then over again, the task of creating these aspects stays some distance much less easy than for up to date games, which regularly come with dedicated pattern kits designed for modders’ exhaust. So what is it that retains the NAM group and its fellow modders working on SimCity 4, painstakingly enforcing fresh aspects and sorting out the limits of what’s imaginable?
Lucario Boricua says that working on the game this day feels love “standing on the shoulders of giants.” The many years of labor that modders grasp place aside into the game present a platform for this day’s creators to push the game into areas its designers potentially below no circumstances imagined: “We’re all for doing innovative issues that redefine what’s imaginable.”