I've already implemented a collectable heart thing, instead.
The "After beating the first boss" bit might be too tricky!.. Depending on what the boss is like.. I still haven't done that, yet!!





I've tried a number of different styles for the life system, but have inevitably ended up with the good old classic life system. It's odd that I've chosen this, given how settled I previously was on the "One touch = dead" system.
Basic stuff. Start with 2 lives per level. 2.5 second of shield when hit. Dead after all lives are gone.
I'll still be sticking extra-lives in curious places throughout the game.