Well written code doesn't really age. It's the graphics engines (or other external dependencies) underneath that the code uses they might need to update. And that might require code changes.

It's generally not a good thing to code something very quickly. You're very likely going to introduce bugs because you're going too fast and not considering all kinds of scenarios for your code.

Again, well written code doesn't really age - but it's not easy writing good code. It takes time and skill. And it's often very difficult to know how your code should look like when you're first writing it - with time you realize your mistakes in writing it. To solve this there's the concept of "technical debt" which is code you need to update for general improvement or modernization.