A sort of expansion is available for Advanced Invaders. Could be interesting to those interested in game development :)
Binary Void is а tutorial template Unity game project, derived from Advanced Invaders. Nearly everything that Advanced Invaders game offers you can learn how to make in Unity, with the help of this, in-detail explained, project. It comes with various assets, which include 6800 lines of organized and commented C# code and a 90-page PDF walkthrough that explains all those assets, in approachable and friendly way to common gaming folk. This project features and explains a lot of elements useful for variety of games as well as that general structure that often accompany games of whatever genre (such as saving stuff in files, tweaking options, rebinding controls within the game, etc.).
Check Advanced Invaders ITCH.IO page to find out more.
Oh and Advanced Invaders is on 50% discount for a week in honor of Binary Void release! :)