If you want to get some of the flavor of Portal, somebody has created a 2D version of Portal in Flash – after you click this link click “PLAY THIS GAME”. It is only a little taste of what the Vavle game is, but might help folks with visualizing what Portal is. Also this video is a fun visualization aid.
[youtube]http://youtube.com/watch?v=GWzmL05OlYA[/youtube]