Cities: Skylines II is a 2023 city-building game developed by Colossal Order and published by Paradox Interactive. The game is a sequel to 2015's Cities: Skylines and expands upon many of its simulation factors such as simulated city and population sizes with improved traffic AI and management schemes. It was released for Windows on 24 October 2023, and is planned to release to PlayStation 5 and Xbox Series X/S in Q2 2024. Critical reception praised its gameplay but criticized its performance requirements and other technical flaws.
 Like its predecessor, Cities: Skylines II gives the player a virtual plot of land to create a city within. Players can lay down roads, zoning, utilities, and city services to bring in residents and businesses. The player can set city policies like tax rates and ordinances to influence how the city grows, from which they also receive funds to continue to expand the city.
 Initially the player is limited to nine tiles of space to build on but can expand out by purchasing additional tiles with city funds as they achieve milestones. Whereas the first game was limited to nine tiles covering 36 km2 (14 sq mi) of area (81 tiles with user modifications) and the remastered edition to 25 (100 km2 (39 sq mi)),, Cities: Skylines II allows players to build out to 441 tiles representing 159 km2 (61 sq mi) of area, meaning each individual tile is substantially smaller. Unlike the previous game which was limited to around 65,000 citizens, the number of citizens that can be directly simulated in Cities: Skylines II is limited only by a player's computer or console specifications. Each map included with the game is based on a preset climate that influences weather behavior. Both the weather and the behavior of the city population follow annual and diurnal cycles, with each in-game day/night equivalent to one month of simulation time. Depending on the climate, the winter months may bring snow and other cold conditions, while summer weather may bring excessive flooding and tornadoes. Such disasters can be mitigated with additional disaster response facilities and services within the city.
 Cities: Skylines II improves and expands upon the robust city building mechanics fans know from the original, including fully realized transportation and economic systems, enhanced construction and customization options, including American and European styles, and advanced modding capabilities. Players have more fine-tuning control of residential, commercial, and industrial zones, including more zone types such as low-income residential and mixed-use residential/commercial. Signature buildings can be unlocked by reaching specific milestones and can impact the land value and other properties of whatever zone or city they are placed in. Rather than purely distance as in the first game, the simulated citizens use more intelligent methods to determine traffic routes, using route length, costs, comfort, and agent preference. Services like police and fire stations can also be assigned to specific districts to improve their response times, in contrast to the first game. In addition to public safety services, education, and trash management, Cities: Skylines II also adds in services for telecommunications, welfare, and death management. These services can now be expanded through upgrades of existing locations rather than having to build a separate service building. Passenger and freight transport options are more flexible, allowing for importing and exporting to other virtual cities, and rather than unlocking certain transport options based on city size, Cities: Skylines II has a technology tree on which players can spend development points to advance and unlock desired transport options.
 Cities: Skylines II continues to use the Unity engine, like its predecessor.
 Cities: Skylines II was revealed on 6 March 2023, as part of the Paradox Announcement Show 2023. Adding to the base game, eight separate downloadable content packs are already slated for release, including the San Francisco Set, Beach Properties Asset Pack, two Content Creator Packs, the Bridges & Ports Expansion, and 3 Radio Stations in the Ultimate Edition option on the Windows, Xbox and Playstation online distribution apps.
 Unlike the first game, Cities: Skylines II was originally targeted to launch on both computers and consoles at the same time, but on 28 September 2023, Paradox Interactive announced that the console versions would not ship as expected on 24 October and that their release had been delayed to spring 2024. They further announced that preorders for the console releases would be closed and that all existing preorders would be refunded to the purchasers. Colossal Order explained that they were delaying the release to improve the quality of console gameplay and the optimisation of both console and Windows versions. Alongside the delay, they also announced an increase to the minimum specifications of the PC version of the game. In the week prior to the PC release Colossal Order further stated that the performance of the game may not be up to expectations at launch, but that they had planned a series of patches to improve this.
 Colossal Order also stated in October 2023 that while the game would support user modifications as with the original, mods would only be made available through the Paradox Mods library, which allows for cross-platform support, rather than through the Steam Workshop that the first game had used. At least eight building style packs, developed by popular content creators from the first game, will be made available for free through Paradox Mods. This modification support is not
offered to everyone at the time of initial release, per the publisher's announcement. 
 Third party mod managers, such as r2modman, allows one to install mods from third party mod repositories.
 Cities: Skylines II received "mixed or average" reviews from critics, according to review aggregator website Metacritic. At launch, the game reached more than 100,000 concurrent players on Steam. It received "mixed" reviews from players, with the majority of the reviewers criticizing the game's various performance issues and noticeable bugs.
 Leana Hafer from IGN said that although it has new enjoyable systems, the game can get better with post-launch content, stating "it feels like playing a beta, or a very early Early Access game." Ed Smith from PCGamesN describes how initial peaceful gameplay gave way to "supreme frustation and rage". In his Cities: Skylines II review, which scores the game seven out of ten, he concludes: "Something personal is lost in its larger scale while performance problems spoil the beauty, but this could one day become the superior city building game." Smith compared Skylines II to SimCity (2013), saying that both games experienced similar playability and performance issues.
 The game was nominated for "Best Sim / Strategy Game" at The Game Awards 2023.