Cities: Skylines 2 boss says they 'completely overestimated' the Unity engine's capabilities

In the wake of Cities: Skylines 2's shaky launch and mixed reception, developer Colossal Order and publisher Paradox Interactive have parted ways, with a new dev, Iceflake Studios, stepping in to continue patching the city builder.

The issues with Cities: Skylines 2 ranged from poor optimization to an absence of modding support to a perceived lack of features (at least when compared with the original) to its Bridges & Ports expansion being delayed for more than a year.

At least some of Skylines 2's struggles both during development and post-launch were due to the Unity engine the game is built on, according to Colossal Order CEO Mariina Hallikainen. "We completely overestimated the engine's capabilities at the beginning of the project," Hallikainen said when we talked earlier this month.

"When we started to work on the sequel, we very much built all the plans toward features that were not finalized in the engine. So, we basically wanted to future-proof the game. We were all the time thinking that we will be working on this game for possibly up to 10 years, post launch," Hallikainen said.

"We basically looked into the very new technology that Unity was offering, and that turned out to be a mistake, in the sense that there were features that didn't actually fulfill the promise," she said. "We ended up in a situation in the development where we had to build much more things to either replace missing features or something that [wasn't] working.

"This was something that we very much now understand, that our mistake was to bank on something that was not yet proven, and that was a huge hindrance throughout the development of Cities: Skylines 2."

Some of the issues with Unity at the time, Hallikainen clarified in an email after our talk, were "the general instability of the engine, HDRP shader pipeline missing core features like the interpolators, and the ECS [Entity Component System] long running job support (the lack thereof)."

In my 2023 review of Cities: Skylines 2, I noted some performance and optimization problems as well as a general sparseness to its features—though I definitely didn't expect the city builder to run into quite as much trouble as it did post-launch.

Interestingly, despite the issues during Skylines 2's development and launch, it sounds like Hallikainen doesn't bear any ill will toward Unity. "We have a great relationship," she said. "We definitely had good communication with Unity throughout the development of the game, and they did the best they could to help us. Overall, what I absolutely want people to understand is that everyone at Colossal Order, Paradox, Unity, we all did the best we could under the circumstances."

Now independent again, Colossal Order is currently working on a new game, though Hallikainen wouldn't give me any details about it—other than that it's "in the simulation genre," it's being made for PC, and it's being made, once again, in Unity. "We're very much happily using Unity," she said. "It is just that we are going to be using it in a smarter way."