whats a game that you got significantly far into, only to realize you were doing something wrong or missing a key feature/ability altogether?

When I played the original AoE2 I was completely unaware of the strengths and weaknesses of the different units. I just build whatever I found to be coolest and wondered why I struggled so much.

Only when I bought the Definitive Edition much later I looked that up.

For my defense, I was ten back then.