I really like the gameplay, format, and the colors. I just wish the numbers were a little bit easier to read. The black blends in a little bit too much to the gorgeous dark blue background, particularly in some areas with the monkey pattern behind it.
The game is really cool. I love the creativity. What a great approach to a zombie game. I wish it was a little less repetitive though. I want to beat it but sometimes I get tired of doing the same thing over and over.
To use the portal, walk onto it, then click on it, then click on the name of the level you want to go to. "Level 1" will probably be the only one available, then when you defeat it, "Level 2", etc.