OpenRA

Thanks @Cmd. Matt, I did the same, navigating through the code, follow references, analyzing procedures and so on. But what I supposed is that a such strongly designed code should be implemented based on some software engineering study or in the minimum some pattern design consideration. Do you say ...

Is there any documents about software design, diagrams or any stuff may help understanding the code right way.
The code is so huge, and is really very good code. but I spent about 2 months till now, and still there are some classes' relationships not clear.
Any suggestions?