Modding is in Cities: Skylines' blood. For a year of its 18-month development one of the team's two programmers worked solely on making the game's mod tools. Developer Colossal Order was confident mod support would ensure Skylines would foster a community around the game.
The team was right.
Since Skylines launched in March it's sold more than a million copies and more than 45,000 new buildings and hundreds of mods have been created by the community.
For years major developers have been dropping support for mods on their games so it's great to see a team work to put mods into its game and prove there's a huge community waiting for the chance to make mods.
However, it's not the only big mod story of 2015. Shortly after Skylines' launch Valve and Bethesda tested a paid mod scheme with the Skyrim community. Mod creators were given the power to charge people to download and install their mods. There was an uproar from the community, for years they had been getting mods for free and they didn't want that to change. Valve ended the scheme early, which pleased the disgruntled community but angered a number of the modders who lost the chance to earn money for their work.
That paid mod scheme may have ended but it was a first attempt. Last week I sat down with Mariina Hallikainen, Colossal Order's CEO, Skyline's developer, to see if she thought paid mods had a future. “I can only answer this from my personal opinion,” Hallikainen insisted. “I can’t speak for Paradox or Colossal Order officially. If we were ever to bring a feature like that to our games, we would have to make it extremely robust. We would have to put a lot of effort to make sure modders couldn’t steal each other’s mods and make it in a way that when we update the game nothing breaks.
"I think it’s good to give options to the modders and players. It’s never good to limit that."
The trouble, she says, is "when money is involved you have to make sure everything works".
"We have made the modding tools in such a way that if you use the official modding api and we update Skylines we know which parts of the code people can tweak and we can make sure when we update nothing in their mod breaks. But, because modders are so skilled, some have disregarded the modding api completely and have gone so deep in the code we have no way of knowing what parts they have touched. For example, there’s this Traffic++ mod, our latest update broke it completely because it had an option panel in the menu that we didn’t even consider–and we can’t, there’s 45,000 items, hundreds of mods, we can’t go over all those to see if we’ll break them. It made the game completely unplayable for the players who had this mod. The players had to remove the mod. The modder was quick to fix it but still people were panicking because Colossal Order had put out an update and now everything was broken.
"Think about if you had paid for those mods: how you would feel about the modder, about the player, and about us."
Stability and copyright are the two biggest challenges for paid modding. Until now the lack of a price tag has made players more forgiving of bugs and modders more willing to share their work.
Despite those challenges, Hallikainen says "I believe that in the future it’s going to be a thing that many games will do and it’s a positive thing."
Editor's note: travel and accommodation were arranged and paid for by Unity.