Screeps is a programming game in which you make a bot in JavaScript to play an RTS. I wouldn't recommend it as your first JavaScript project, but once you get some experience, I think it could be fun.
I suggest you Solitaire GC Online app for Android phones and tablets. It's free and my favorite because you can play and compete against other solitaire online players. https://play.google.com/store/apps/details?id=com.grebenetz.solitaire