the game code is open source. you can take and use it anyway you want. i made this game with unity. i recommend watching code monkey intermediate youtube tutorial. it was very helpful to me. i suggest you learn these design patterns.
1. singleton (it works great with unity but it has a bad reputation)
2. state pattern
3. object pooling
4. observer pattern (events)
5. solid principles (mostly understand interfaces and separation)
the code does not have to be perfect, it just needs to work and it should be open to further change. good luck.