Easily one of the most impressive graphics engines on the market is sitting right there, yet the new Horizon MMO is skipping it entirely. Instead, Horizon Steel Frontiers, NCSoft’s MMO, is being built on Unreal Engine 5 rather than Guerrilla’s in-house Decima Engine.

Unreal Engine 5 has exploded across the industry as the default option for a huge number of studios, and that rise has caught many people off guard. Some of the best games of the last decade have indeed been powered by Epic’s technology, but the fifth iteration has been under fire for its shaky performance and long list of technical complaints. None of that has stopped companies like NCSoft from backing it, and that is precisely what makes their choice to use UE5 instead of the widely praised Decima Engine on Horizon Steel Frontiers so eyebrow-raising.

For anyone who has missed the last couple of days of news, Horizon Steel Frontiers is the latest entry in the Horizon universe, only this time without Aloy in the lead role and without a traditional PS4 or PS5 release. NCSoft, the publisher behind Throne and Liberty and many other online titles, is taking Guerrilla Games’ post-apocalyptic setting into a fully fledged massively multiplayer online project, the first MMO in the franchise.

In that context, lead developer Sunggu Lee answered one of the most common questions about the project in an interview with IGN: would the game be running on the original Decima technology? The response, as already hinted, was a clear no. According to Lee, there is currently no other engine like Unreal Engine 5 that allows them to “deliver stunning visuals and a smooth multiplayer experience on both mobile and PC” at the same time.

That does not mean Decima is unproven, of course. Although it has never had to support a true, large-scale MMO, it powered games such as Killzone: Shadow Fall and RIGS: Mechanized Combat League with competitive multiplayer modes, and visually, it speaks for itself, with Death Stranding 2: On the Beach standing out as one of 2025’s most striking showcases of what the engine can do.

Outside Guerrilla Games, Almost Nobody Knows Decima Well

So why not simply stick with the Decima Engine? Although Guerrilla Games appears to have been fairly open in sharing Horizon assets and documentation, the simple explanation is that real-world experience with the engine barely exists outside the studio. Decima is maintained by a relatively small, closed circle of programmers, technical artists, and designers whose intimate knowledge of the code is a big part of why it performs so well. Unreal Engine, by contrast, is a widely adopted, thoroughly documented toolkit that thousands of juniors and veterans already know how to use. For many studios, that makes UE5 the default pick, because it is easier to hire and train people for it than for a proprietary solution. In fact, a lot of newcomers arrive on teams already familiar with Unreal, having learned it on their own long before their first professional job.

Players Are Wary Of Unreal Engine 5, And They Have Reasons

Lee does not dispute that Decima is an “incredible” engine, yet the decision to rely on Unreal Engine 5 immediately triggers suspicion among many players. UE5 has a reputation for chewing through hardware resources, suffering from optimization headaches, and struggling to keep frame rates stable, especially on consoles and mobile devices. As a result, what was once marketed as a guarantee of spectacular graphics has, for part of the community, turned into a red flag that often signals a long list of bugs and performance issues.

That is why Daniel Vávra, head of Warhorse Studios and director of Kingdom Come: Deliverance 2, has argued that Epic’s engine should really be reserved for projects that are designed to push high-end hardware to its limits, since in his view it is a poor fit for mid-range or low-end systems. He has even warned that The Witcher 4, which will abandon CD Projekt RED’s in-house RedEngine in favor of Unreal Engine 5, could turn into “a development nightmare”, because building huge open worlds is one of the areas where the engine struggles the most.

Source: 3djuegos