Some developers are seriously considering de-listing their games from online shops when the Unity Runtime Fee kicks off at the start of next year, meaning some titles built on Unity could end up being temporarily — or permanently — unavailable. Here's what developers are saying about the Unity Runtime Fee on social media, and what games could be impacted.
It depends.
I’m working on a game with Unity and the software design has been done in a way that keeps most the game itself as data, and uses the Unity stuff mainly as something to display multiple views on the state of the data (a 3D view of the game space, multiple UI elements diving into slices of the data an so on) - basically a Model-View-Controller Architecture, so moving from Unity to something else doesn’t require a rewrite (in fact such structure makes it possible, for example, to with some ease change the game’s visuals from 3D to 2D), though it would still be quite a lot of work.
However my game is survival-management in space (within one or more generated star-systems, so it was simplified down to a 2D plane) which doesn’t relly on Unity things like terrain, navigation meshes or even colliders to constrain the movement of objects in the game, so calculating “what happens next” (say, the movement of planets or the guidance of ships going from planet to planet) gets decided using Maths at the data level without going through the Unity layer, and Unity is mainly the means to get user input comes and the layer that gets updated with the state of the data at the end of each cycle (i.e. game objects get moved around) which it the uses for rendering.
Other games which are not reliant on Unity to do the heavy lifting for objects interactiong with other objects on a 3D space, such as 2D platformers, can probably use a similar architecture, but for example something like Valheim or Planet Crafter (were the player controls a humanoid avatar on a 3D world which is mainly terrain) is probably much harder to move out from Unity,
Not to mention I’m sure they use third party tools to help with things. Bigger games like Genshin Impact for example, are on an older version of Unity where they heavily modified the engine to suit their needs. That would take a tremendous amount of work to move, and they’d have to redesign their entire graphics pipeline. Which also Godot has gotten better, but is still far behind the others in terms of high end graphics. That’s why it’s usually seen as the go to for indies, and not so much high end games. Also they don’t plan on making anything like DOTS, but I’m not sure how relevant that actually is.