If you are feeling like you can't play something you want, you can simplify like they did for this octopus. The "piano" for the octopus was in a key so that no matter what note was played, it would sound okay. Similarly, you can restrict yourself to only black keys or only white keys and your simplified song will come out easier. Other simplifications, play any two notes that are one key separated from each other (never right next to each other), called thirds. Just a way to start noodling.
Thanks for the inspiration !