Alter Arsenal adds new items to the game like:
-Blast Bomb: (power) bombs can remove crumble blocks
-Boost Ball: enable speedbooster in ball form
-Chain Spark: keep speed charge when shinesparking into a wall
-Hyper Mode: drain reserve energy to fire charged shots non-stop
-Ice Missiles: regular missiles deal more damage and can freeze enemies
-Paradox Beam: able to equip Spazer and Plasma at the same time

It also revamps the health system.
Energy number display is % of total life (99 for full) instead of remainder of e-tanks.
Starting health is 300, max is 700 and enemy damage is adjusted accordingly.

The total amount of collectible items is now 105 while keeping most of the well known vanilla map in tact.