In vanilla Super Metroid, a "spikesuit" is the name of a glitch that gives you a stored shinespark that you can use later (similar to the well-known "blue suit" glitch, but you lose a blue suit if you run). However, when you have a spikesuit, you need to move carefully in order to not set it off accidentally.

This hack is simple: you always have a shinespark charged, ready to be set off.

Shinespark health drain is disabled, and the crash animation is shortened to 10 frames, so there's basically no downside to intentionally shinesparking everywhere to get around faster, but this is offset by the need to be careful in your movement.

The "Hard Mode" re-enables health drain, and the full crash animation.