First Javascript Playground

Hello everyone. I’d like to ask for a feedback about this simple Javascript playground. You can find it here.
It consist of a simple window, a text input and three buttons: one for encoding, one for decoding and the last (pretty intuitive) to clear the window. The user can choose between 5 games from a drop-down; the string passed to the text input is retrieved and then transformed accordingly; the Encode button encodes the string, the Decode ‘translates’ back to a simple string. The output is shown on the window. Its a pretty simple project but I had fun writing it. It’s my first project with Javascript. There are quite a lot of scenarios where things could go wrong; the project relies heavily on a correct input from the user. I may choose to fix the little bugs in the script, the next days; also the CSS is quite minimalistic; I may add something here too. Well, enough with this long post: please let me know what you think about it

To improve the UX,

  1. verify your email addr with codepen so your page can be viewed full screen
  2. since you’re showcasing your playground, link to the full view rather than the editor

Done. Thank you. Any thoughts about the project?