See those tiny moving nyan buttons in the left hand upper corner? Click them to select a part to color. A color palette should come up, where you can chose what color to make that part of the nyan. The squares in the bottom left corner are all official PopTart flavors; click them to change the Nyan's body. The five circles in the bottom right hand corner are backgrounds. Click them and the background will change. The six sliders are to change the colors of your nyan's rainbow. They each change a different streak of rainbow. The circle with the arrow resets the nyan to the classic nyan. The die create a random nyan. The audio button can turn off or turn on the music. The cat face button underneath your Nyan will let you give a name to said Nyan. When you're all done, press the arrow in the right-hand bottom corner for the Nyan challenge with your own nyan.
I don't own Nyan cat, Poptarts, or whatever. I did draw the custom Nyan Cat sprite, as well as all the buttons and backgrounds, and I created this all by myself. Time estimated to complete project; 24 hours. *You may have to click the flag twice for it to work properly. *Please tell me if there are any glitches! *It may take a while to load and/or lag slightly. My apologies for that.