Hello there,
here is a game im working on for quite some time now:
The game already includes different levels with different enemy types and a shop after every level, where you can spend money to upgrade new lasers and missles. It also has joystick-input implemented, so you can play it with keyboard or xbox-pad 360 without having to switch the input method in the menu settings.
The Codebase discussed in the book "SFML-Game-Development-Book" (
https://www.amazon.de/SFML-Game-Development-Jan-Haller/dp/1849696845) was a great resource and help for building it.
Let me know what you think so far.