Pagoda is an online database of links relating to Adventure games that I've created and maintain. The initial reason I did was I wanted to find where I could buy a given Adventure game, but Pagoda now has a life of its own. I'm encouraged to continue by occasionally hearing of people using Pagoda to find information about games.
I've tried several times to classify the games listed in Pagoda but each time found the exercise problematic. A number of websites have their own schemes of classification and good for them. Recently I've added into Pagoda the concept of a group of games which is at least a better defined concept. From a lot of reviews it's hard to glean what a game is like. For instance some reviewers won't mention if a game has arcade sequences.
Pagoda is maintained by scanning a number of websites for links to reviews and walkthroughs etc, then matching those links to games already in the database. New games are added as found.
Challenges are variant names for games (for example "Atlantis 2" being also known as "Beyond Atlantis"). And when websites decide to restructure themselves which they're at perfect liberty to do, it just causes me to have to redo that part of my database.