I started this game as my first own game and would love to have ideas on what I need to add to it to make it more fun, challenging and probably level like.
I think its a decent app.You should do what comes in your mind,just go with your intuitions because you have developed the app and you know better than any other what you can do to make it better.
Please add the things that are more interesting and like by people mostly today. For do so you can take help of reputed games. You can also organize the poll questions online by which you can get people ideas.