Terrarium is a project mainly written in JavaScript, it's free.
Nothing particulary innovative here, just a learning experience. Adapted part of chapter 8's terrarium exercise, and used some exercises from chapter 13 to display it onto a table and add a controllable player character.
Directions: just load terrarium.html in a web browser, and control the '@' symbol with the arrow keys. You may have to click on the terrarium before the arrow keys will work.