Can any of my older/more learned readers recall the names of any of those classic programming magazines? The kind of thing that would feature little snippets of BASIC code and simple algorithms. I'm still toying with roguelike stuff and it's tough to get a grasp on things. There are a few reasons for this:
1. The old code is in very old languages. Not only can they be very hard to understand but the implementation may be so vastly different that it won't be useful with a newer language.
2. The newer/maintained code has grown incredibly complex and fragmented. You have to understand every single part if you want to extract even one piece of it.
3. Some of the really inventive, new stuff isn't open-source. Both Incursion (which has a very robust implementation of the d20 SRD in it) and Dwarf Fortress (which is mind-boggling) are closed-source with no apparent plans to open-source. I don't think Dungeon Crawl Stone Soup is open-source, either.