Cryptozookeeper is an XYZZY Award winner, and is one of the biggest games out there in terms of content, especially in terms of NPC content.
You play as a character who is sucked into a world where you can blend together DNA and create new monsters, who then fight each other in a pokemon-like system.
The system takes center stage story-wise, but not mechanically. The game is structured in a series of 'episodes', each of which results in new DNA for your devices.
The game has a ton of characters, many of whom constantly follow you around and talk and joke.
The implementation is selective; some parts are extremely detailed, while many synonyms and scenery descriptions are omitted.
This game is truly monumental. It also has a great deal of profanity and suggestive language.