Gape “SimCity four” on YouTube, and in addition you’ll see gamers developing multilevel highway interchanges and intricate railroad networks, or presumably even a swooping flyby of a sprawling metropolis. None of those functions came with the fashioned game, which was as soon as released valid after the turn of the millennium. They’ve been developed slowly and painstakingly over the 22 years since its liberate by devoted aficionados — a thriving group that continues to push the game’s limits.
The work is a labor of love, and it’s loads of labor and love. Modder Tarkus says that in spite of every little thing 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 four’s possess sequel, which was as soon as released in 2013 and merely called SimCity. Modder Ulisse Wolf says that, for him, it’s in some way a query of group. Perhaps due to the the game’s age, he finds that SimCity four followers are “more outmoded … guaranteeing you a peaceful quandary to reside in [peace] with other participants.”
SimCity four was as soon as released in 2003, the fourth in game company Maxis’ series of metropolis-constructing games. It was as soon as reasonably successful, garnering obvious experiences and promoting well ample for Maxis to liberate an expansion pack later that year. The flexibility for gamers so that you just can add their possess convey to the game was as soon as a key half of SimCity four’s appeal from the originate: it came with a quandary of tools that allowed gamers to gain and add their possess constructions to their cities. Avid gamers soon began sharing their creations online by the consume of exchanges hosted on fan sites love Simtropolis and SC4 Devotion (now defunct, however relaunched recently as SC4 Evermore), in addition as discussing pointers and ideas in the accompanying forums.
“It grew to change into decided to me that if I wished to behold more happen on the transportation modding entrance, I wished to search out out originate things for myself.”
Avid gamers soon began to behold past the officially supported methods of including their possess convey to the game and wondering what else would maybe very well be carried out. May well also the game’s highway gadget be expanded? What in regards to the railways? Early modding efforts were made more uncomplicated by the manner the game retail outlets its info, which, as modder Matias93 explains, is in a database whose structure was as soon as shared with old Maxis games. The database retail outlets info in regards to the game’s varied parts: for a form of highway, the database would grasp entries for every little thing from which textures to exhibit on mask when the participant positioned the highway correct down to how great traffic the simulation would enable it to lift.
The game’s built-in tools offered no manner to access this database, so the group developed its possess — no easy activity, as Matias93 explains: “[This] required the construction of a veritable suite of tools in a quandary 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 manner around the database, on the opposite hand, they started to search out entries for programs that weren’t in the game: functions that were either unfinished or by no manner implemented. “SimCity four presentations decided signs of getting gotten much less convey and expansions than its creators [intended]. Whereas a majority of those parts are practically irremediably broken … many others were reasonably at attain to be repurposed,” Matias93 says.
Using the tools they’d developed to tweak existing entries, modders were in a quandary to earn the rudiments of those unfinished functions into fully original ones. One among the first such functions to be repurposed was as soon as an unused highway form, it sounds as if intended to be a dust highway for consume in rural environments. SimCity four comes with several forms of roads for gamers to quandary of their cities: suburban streets, two-lane roads, two-lane one-manner roads, four-lane avenues, and highways. Avid gamers soon chafed against the obstacles of the latter: there was as soon as no manner to earn a highway with deal of lane widths, and connecting a highway to a highway community required the consume of one of several prebuilt interchanges. Avid gamers who wished to manufacture and earn their possess interchanges, or make highways with deal of widths, were out of ideally good fortune.
The invention of the unused dirt highway meant that there was as soon as location for yet every other highway form, and modders ancient it because the basis for what grew to change into the “precise highway” mod, a more flexible and customizable change to the game’s built-in highway gadget. Without discover, gamers had a couple of highway widths to take from, in addition as modular pieces they would maybe maybe consume to earn their possess custom interchanges.
Tarkus recalls discovering an early model of the mod in 2006: “I used to be as soon as absolutely floored. [Even though] it was as soon as an extremely restricted mod at the time, I would maybe maybe allege it had skill.” Staunch-lifestyles commitments took him a ways flung from the game for most of that year, and on his return, he chanced on that construction had stalled. “It grew to change into decided to me that if I wished to behold more happen on the transportation modding entrance, I wished to search out out originate things for myself.”
On the present time, Tarkus is the lead developer on the Network Addon Mod (NAM), a sprawling equipment that functions the RHW mod along with a broad quantity of alternative transport-based convey: pedestrian malls, a original railway gadget, roundabouts, canals, bridges, and underpasses, in addition as a comprehensive reworking of the game’s traffic simulator. The mod stays in active construction — its Forty ninth model was as soon as released in March 2025 — and is maintained and developed by a continuously transferring and evolving crew, whose membership spans the globe.
Lucario Boricua, who spearheads construction on several of the mod’s functions, lives in Puerto Rico and is a civil engineer by day. He estimates that, as of early 2025, the crew has around 25 stout-fledged participants, along with other half-time contributors, playtesters, and so forth. The group is salubrious in in vogue, too — participants catch in both the lengthy-operating forums and newer channels love Discord, and both are normally good areas to use time, with veteran participants welcoming original followers and what Wolf calls “political bullshit” particularly absent.
It’s no longer valid the NAM that stays in active construction, either. In 2025, SimCity four modding continues to conform and encompass original possibilities, largely because of improved access to the game’s source code. Matias93 explains that “the first 15 years of modding, more or much less, [had nothing] to originate with coding per se.” As yet every other, they intriguing customizing and lengthening the game’s databases. Then again, that modified in the 2010s because of two key inclinations.
The principle was as soon as the liberate of a portion of the game’s code, offered by the tiring Paul Pedriana — the game’s fashioned chief programmer — in step with a demand from the group. This allowed for the reimplementation of a couple of of the game’s inner debugging functions, which grasp been indubitably cheat codes that allowed builders to originate things love snappy quandary up cities with out tense about practicalities love having ample in-game money, quandary particular constructions presently, and loads of alternative precious functions. Then, in 2019, a sixty four-bit macOS port of the game was as soon as released — with an unexpected bonus for modders. “Quite a lot of the game code [was] legible on the released executable, allowing modders to name certain imaginable hooks to work with,” Matias93 says.
Modders proceed to lack stout access to the game’s code, however even restricted access has allowed the consume of tactics that can grasp in any other case been no longer doable. Essential among these is the consume of dynamic link libraries (DLLs), which enable custom code to be loaded into the game’s executable at runtime. The flexibility to jot down custom DLLs has allowed modders to fix lengthy-standing bugs in the game — most particularly, one notorious misfortune that would maybe maybe consequence in set game corruption in colossal cities. It also allow them to dream up functions that don’t grasp been imaginable in any other case: recent additions comprise a 3D camera, the reimplementation of the game’s lengthy-broken water gadget, and a Steam Workshop-esque interface for finding and downloading custom convey.
Then again, the direction of of developing these functions stays a ways much less straightforward than for contemporary games, which continuously approach with devoted construction kits designed for modders’ consume. So what is it that retains the NAM crew and its fellow modders working on SimCity four, painstakingly implementing original functions and testing the limits of what’s imaginable?
Lucario Boricua says that working on the game presently time feels love “standing on the shoulders of giants.” The a protracted time of labor that modders grasp put into the game provide a platform for presently time’s creators to push the game into areas its designers potentially by no manner imagined: “We’re occupied with doing modern things that redefine what’s imaginable.”