The requirement is to create a horizontally scrolling shooter game with no weapons. I thought that I could have the enemies shooting at you and you could use their own bullets against them. If you had a shield, you could reflect the bullets back.
I created a quick demo and generated some bullets. The first problem was how to work out which direction to bounce the bullets back. After a bit of tinkering I found the best way was this -
1) Get the direction between the playerx,y and the bulletx,y
2) Invert this (add 180 degrees)
I tested out and it works OK, I think. Note that in the video, the bullets don't just get bounced in the opposite direction they are travelling, with a bit of skill you can actually 'aim' the bullets towards different parts of the screen, depending on where they hit your shield. A nice demo, but can I turn it into a game???!!
Rad idea! I think to game-ify it, a big key will be giving the player incentive to avoid using their shield. Perhaps using shields decreases your velocity or saps your health?
Either way, excited to see how this one goes.