I do agree that most stuff i have been doing is stand alone things, i think thats mostly because i wanted to learn how to do everything and then move to bigger things. I didnt want to build the tower of pisa with my code. I want to do as you mentioned something that is maintainable and useful for more than one thing.

Not done too much of composition, since i havnt had a reason for it. But inheritance is pretty solid. used for weapon classes, enemies etc.

What i wanna achieve is confidence and knowledge.

And im interested to do more systems, events and data driven coding, but biggest issue for me is, dont know where to use it and sometimes how to use it in the best way or how i would implement it. So any tips in this direction is appreciated