When you say app, do you mean writing things for phones, or just games for PC? What kind of games do you want to write? Do you want to learn to write small games for yourself, medium size games that could take several months? Do you want to learn what you need to know to go and work for a major games company?
I would like to start with PC games. At present i don't have any experience in writing Game app, so I would like to start with small games. Actually i want to keep myself busy and try/explore new stuff. At present i'm working as embedded eng and enjoying my work, so i don't have any intentions to join any gaming comp.