This is my entry for the Non-shooter side scrolling shooter GameDev Challenge
I started way late so it's a relatively simple game that meets all the minimum requirements detailed here: https://www.gamedev.net/blogs/entry/2266997-ping-zap-zing-side-scrolling-arcade-shooter-challenge-without-weapons/
Multiple waves of enemys spawn. Avoid getting shot and try to get the enemies to shoot themselves. There is an invincibility power up in each level. Beat both levels without dying and you win the game.