What are the best tools for learning a new codebase?

[Ganemi]

This is pretty intense.

http://i.imgur.com/aKWZfVj.jpg

That's not the particular portion of code I'm skimming through, but is there any better way to understand the code that I am using?

[D-Meat]

Eeeh ... Your brain ?

Personally I just dig where functions are connected using the search tools of my beloved notepad++.

One really useful thing is to print up with colours the variable definitions (specially the gentity_t) so you can check it up anytime !

I remember writing down some functions to really tick in what's going on.

[Eraser]

Get a good IDE like Visual Studio (the community edition is free)

What I usually do is come up with some very simple features I'd like to add or edit, something that won't require you to refactor half of the internal data structures. Preferably it's something that you can point at in a user interface or in the game and say "I made/changed that". It allows you to learn some of the flow through the code. That way, you can gradually dig deeper and make more abstract changes in due time.

[Ganemi]

I'm finding doxygen, winmerge, and vs10 pretty useful for figuring things out.