TiTs was half made because CoC's code-base was becoming a nightmare to work on, because it had been organically grown for years by a guy who started off barely knowing how to code, and having no formal training in organising code (of what little there is to be taught in CompSci). And secondly for a new change of scenery, fresh start, and clean break allowing easy addition of new mechanics. IMHO CoC had become fairly complete (especially by adult-internet-game standards) by the time people wound down contributing to it.
Fenoxo is still mostly working on TiTs, his long time friend-writer Savin is now the head contributer for CoC II. Except both of them now have far more experience in designing descriptive games and also have the help of others with more extensive knowledge in code crafting, so the code bases have started off way cleaner.
If you want to make a new text-based adventure game, I would suggest looking at Twine and trying to research what code structures others have used to organise their game, and taking good ideas when they make sense to you. There are a noticeable proportion of games for which you can find the source code for if you look hard enough, sometimes the authors don't care heaps about keeping all the code under wraps because most plebs wouldn't know what to do with it in the first place.
