At its core, Wicked remains a game rooted in the Unity Engine but with a vast range of customisations transforming it into its own thing, hence the nickname - Moonity. This, however, is used only for the game's presentation layer - the graphics you see on-screen. Moon has also built a new simulation engine - built on top of Exit Games' Quantum Engine - to handle game logic, including a fully deterministic 3D physics system for networking, which No Rest for the Wicked will feature at a later date.
What makes this setup work well is the division between rendering and simulation - basically, input responsiveness is separate from frame-rate so, if you're playing on a lower end platform, like a Steam Deck, at 30fps, the game will still feel as responsive as a game running at a higher frame-rate. The visuals, however, are striking. First and foremost, Wicked supports HDR on day one - this is important as we have largely considered Ori and the Will of the Wisps to stand out as one of the best examples of HDR in any game released to date. The HDR implementation is superb and just as intense and engaging as Ori. It makes a gigantic difference if you use an HDR display.