Comment by meheleventyone

There's levels to that though. For example it took me all of a week to write the 2D rigidbody physics system that runs this game:

https://www.youtube.com/watch?v=zVmd2vmZrVA

But it's tightly scoped, there is only really one thing that needs to be dynamic, although it worked admirably with more. We wanted big impulses so could get away from questionable cases easily and could deal with crushing cases simply by exploding the ship.

Likewise the players on the ship running around and the players when they're jetpacking about are all different sub-sets of code implementing that specific behavior.

A lot of "make a game, not an engine" is working out what the minimal thing you need to build is rather than making everything extremely generalized.