In all the talk of graphical downgrades no one seems much preoccupied with 'why?'. Why build something and then proceed to tear it down, piece by piece, in the hope that ever more diminished expectations about the final product won't be severe enough to...
Keep on the move just like you would playing a twin-stick shooter.
Smash as many crates as you can early on to find extra health.
It's worth grinding to get the cash for your evolutions, otherwise you'll end up stuck.