I don't know if they have to switch engines in ten years. You could have made a game in 1997 with Unreal-- I can verify this because I was in a meeting with a

I don't know if they have to switch engines in ten years. You could have made a game in 1997 with Unreal-- I can verify this because I was in a meeting with a demo at Activision where we considered this-- and Unreal is still a viable engine in 2021. Game engines went through a period where they evolved very quickly, and they are still evolving. But the rate of change is slower, like word processors. It starts to make more sense to evolve them rather than replace them.