Your co-worker: Your future self

Even if you work alone, games are so large that you will at some point look at code you wrote yourself with as much confusion as if it was completely new. Programming is never a lonely practice!

You're collaborating, at the very least, with your past self and your future self. If your past self is lazy, your future self will suffer.

Once you finish a piece of code, always take a moment to think: would you understand it right away? Is anything unclear? Are the names you picked and the structure you used communicating the intent of the code?

If anything needs comments for adding details, comment right away. If you're just starting, it might be a good idea to comment the whole structure, every line or almost. This will not only help when you come back to the code, but it will also anchor the concepts in your mind better.