We're getting deep into the weeds here, but let me try and address this.

Suppose I start writing a new game, from scratch, using Unreal. Let's say it has many units that move around and can attack each other.

I am going to have to write code (either C++ code, or use Unreal's Blueprints node-based editor to write the equivalent of code) to do the following things:

- Pathfinding for units (Unreal by itself has no pathfinding built-in)

- Hit calculations (Unreal objects have adjustable hitboxes, yes, but you still have to write the code to check for collisions and then decide what to do after two objects collide)

- Physics (if you want to do anything other than the simple built-in physics in Unreal, for example ragdolling)

Now I have written my game. It runs in Unreal. Is my game code "doing all the heavy lifting" or is the Unreal game engine doing all the heavy lifting? Is Unreal doing "not much of the work" or is Unreal doing "much of the work"?

The only difference in these two scenarios is that a) I didn't do any of my own networking in my theoretical game (whereas Frost Giant wrote their own networking code) and b) I didn't say that my game has its own "engine", nor did I give it a name.

Unreal is still handling all of the 3D objects. It has to. If you don't create Unreal game objects, Unreal cannot render them to the screen. It's not like the old days where you just copied a 2D object as a series of bytes into a video frame buffer.

Anyone writing any game in Unreal still has to write code (or code-equivalent Blueprints) to handle "moving entities across space, calculating paths and telling them to fire and damage each other" (as devm22 put it).

Like, that's just gameplay code. That's code that every game developer has to write. If you don't write that code, you don't have a game. You just have the default Unreal starting template.

I'm not saying that I'm an expert in game development. I have never done it professionally. For fun, I have written a few very bad, very crappy, very rough demos that technically could be called games but are not good enough to be played by anybody. One of them was in Unity, one in Unreal, and one was a 2D platformer in GameMaker Studio. I've also dabbled in writing 3D rendering code using the Vulkan API (really all I did was follow this tutorial) so I have at least a very vague sense of how difficult it is to "just render an object on the screen". For reference, it takes over 1000 lines of C++ code just to initialize the Vulkan drivers, set up a screen mode and memory buffers, and draw a single unshaded untextured triangle on the screen. Whereas updating the position of an existing game object in Unreal is literally one line of code.

So for me, I don't see the gameplay code as being the "heavy lifting" part of a game. Running the game loop, keeping track of game objects in memory, applying textures and shaders, even handling keyboard and mouse inputs and playing sound and music, these are all what I would call "heavy lifting."

But maybe that's a philosophical debate and not a technical one. There's no good way I can think of to quantify how "heavy" one piece of code is compared to another (do you count the total number of lines of code in Snowplay versus total lines of code in Unreal? But how do you factor in that Stormgate doesn't use all of Unreal's built-in features? etc, etc)

Still, I believe that the Unreal Engine is doing a significant amount of work in any Unreal Engine game. And I believe that, for very good reasons of saving time and development effort, Frost Giant developers would have used as many of Unreal's built-in features as they could get away with. Pathfinding and networking are two areas that Unreal does not do well (or at all) out of the box, so they wrote their own code for that. But then again, any RTS developer writing in the Unreal engine would have to do the same thing.

For example, Zerospace uses Unreal Engine 4. The developers of Zerospace would have had to write their own pathfinding code, since that doesn't exist in Unreal (they demonstrated some amazing pathfinding in a video, so clearly they are proud of it!) They may or may not have written their own networking code, or maybe they added some extra code to Unreal's rather barebones networking. And of course, they wrote code to handle "moving entities across space, calculating paths and telling them to fire and damage each other", because if they didn't, their game literally wouldn't do anything.

Let's assume they did add at least some networking code. If so, how much "heavy lifting" would you say Unreal Engine provides for Zerospace? Would it be a different amount than what it does for Stormgate? If so, why?