Well that was harder than I was hoping, but it feels good to have the collision detection working ?

Initially I followed a very good YouTube tutorial by javidx9 - I'd highly recommend his channel. He built his example in his custom engine, but it was clearly presented and fairly straight forward to recreate in C++ with SDL2.

Implementing these methods into Parallax Zoom!! presented the challenge, and as always the issues that I couldn't solve a 01:30am last night were not too problematic at 09:00am after some shut eye. I really should stop coding as soon as I start to feel tired.

Anyhow, it's working now. I get a nice red collision box with each enemy as I ram the player character into them. Next step: explosions!!