Guttersnipe - Carnival of regrets is the first game in a trilogy of humorous text adventure games involving a street kid and her rat. In this one she'll have to deal with a circus and its inhabitants who she'll discover are all but friendly. 

These 3 games are very funny, a mix of very absurd humour and dark comedy. As you play you really get attached to the heroine and her rat, want to discover where all this is going and just as the other characters you're going to meet they're delightfully silly. I also think the reasonable world size, length and puzzles as well as the interface the games are built for which will help you be aware of what you can interact with mean they're a decent introduction if you've never played a parser-based interactive fiction but have been intrigued by this type of game. Some of the more involved puzzles are quite fun to solve too.

All the 3 games are well worth playing in my opinion. Note that the other similar games I played by the same author were too.