A lot of code written toward the "uncle bob" style where you maximize the number of functions has fantastic local clarity, you can see exactly what the code you are looking at is doing; but atrocious global clarity, where it's nearly impossible to figure out what the system does on a larger scale.
Inlining can help with that, local clarity deteriorates a bit, but global clarity typically improves by reducing the number of indirections. The code does indeed also tend to get faster, as it's much easier to identify and remove redundant code when you have it all in front of you. ... but this also improves the clarity of the code!
You can of course go too far, in either direction, but my sense is that we're often leaning much too far toward short isolated functions now than is optimal.
much like microservices.
To some extent you can have that in languages that let you create a named lambda with explicit captures and immediately invoke it, e.g. in C++:
int g;
void doThisAndThat(int a, int b, int c) {
doThis: auto x = [&a, &b] {
...
}();
doThat: [&g, &c, &x] {
...
}();
}
Compare this with enterprise software, which is orders of magnitude more complex than video games in terms of business logic (the complexity in video games is in performance optimization), but whose developers tend to add many layers of abstraction and indirection, so the core business process is obfuscated, or there's a billion non-functional side activities also being applied (logging, analytics, etc), again obfuscating the core functionality.
It's fun to go back to more elementary programming things, in e.g. Advent of Code challenges or indeed, game development.
For people who think game programming is less complex than enterprise software, I suggest the CharacterMovementComponent class in unreal engine which is the logic of movement of characters (people) in a networked game environment... With multiple thousand lines of code in just the header is not uncommon in unreal. And this is not complex because of optimization mostly. This is very complex and messy logic. Of course we can argue that networking and physics could be done in a simple naive way, which would be unacceptable in terms of latency and throughput, so all in all complexity is because of optimization after all. But it is not the 'fun' elegant kind of optimization, it is close to messy enterprise software in some sense in my opinion.
I dont buy it in games like gta, cyberpunk or witcher 3
Smooth side-scrollers did exist on the PC before Keen (An early one would be the PC port of Defender). Moon Patrol even had jumping in the early '80s.
Furthermore other contemporaries of Carmack were making full-fledged side-scrolling platformers in ways different from how Keen did it (there were many platformers released in 1990). They all involved various limitations on level design (as did what Keen used), but I don't believe any of them allowed both X and Y scrolling like the Keen games did.