This applet is less useful for quantitative work. The wavelength and period tools are merely draggable markers that show peak-to-peak distance. Students can not use these to make measurements.
The "discrete to continuous" tab illustrates the results of decreasing the spacing in the wave number domain. The choices for component spacing are limited and the wave packet must be a Gaussian distribution. It is unclear if the purpose is to illustrate the approach to the continuous Fourier transform or to show how a simple wave packet is formed from Fourier components.
The reviewers had a divergent opinion as to the value of the "wave game" activity. One felt it could be used to encourage students to explore the physics while the other felt that it lacked the quantitative aspects necessary for students to make and test predictions.
This applet will require some background and explaining by the instructor for students to learn from it.