Hi! Thank you very much for the explanation! (and for moving to a very simpler IDE)
Now I was able to do everything correctly and to run the game.
Though it's a bit simple, it's very good. (My highest score was 6) And well done. (I suppose, though I'm not a C++ programmer, because I ran the game with no runtime errors, and because I looked at the code)
A few items I would suggest to improve:
* First of all, to tidy up the code (i.e. the target of an if statement goes beneath, and one statement per line). This is good for others who read the code, and for you to keep tidy and enlarge the game.
* Maybe it's better to pass the app object to the Bird and Obstacles objects when you create them, as you pass the Bird object to the Obstacles ones, so then the call to first.draw(); and so would be tidier.
* To use more functions (and maybe classes, and files) instead of writting all inside the main function. This also helps for readability and maintaining and enlarging the game.
Something that has nothing to do with programming itself, you could add keyboard input. And that the bird's flap is milder. I felt like that when I released the mouse button the hang was greater and greater. I´m not sure, but it may be a conceptual issue in the movement() and leftClick() functions.
Having said that, thanks again for your help in the set up. And congrats for the game. It's very good for a begginer.