Swapper is a little play. The CAPTCHA swaps the letters of the word using a moving animation. The number and speed of swaps can be changed. The animation shows when the letters are on bad place. The default color for bad / good place is red / green, but it can be changed.
This CAPTCHA uses the cognitive field of the brain. Funny, that all my friends I was showing this engine could not interpret the challenge. The first good interpretor was a 3 year old child. :)
The weapon of this CAPTCHA: The CAPTCHA misleads the bot. Because the bot has no high level brain function, it tries to interpret only the letters. It does not care about the colors. But basicly the colors and the moves lead to the solution.