100%

100%, which is most commonly referring to the 100% Item Completion speedrun, requires you to collect all 100 items before completing the game. There is one exception to this list which is the Varia Suit, because after defeating Charlie and receiving your fully powered Gravity Suit, you will automatically receive Varia at the same time if you don't already have it, and it counts towards your item percentage. All other 99 items must be collected as intended.

There are quite a few major routing decisions that are all roughly similar to each other in terms of times. Most of these routing decisions are decided based on difficulty vs consistency, or just preferring to do some speed tricks over others. The biggest routing decisions are:

• Early Brinstar vs Late Brinstar
• Ice First Norfair vs Newfair
• Powerbombs Door Clip vs Lottery

For a quick example of how viable each of the above decisions are, the current leaderboard has 1st and 2nd place doing completely different routes for all three of those decisions. Your time in 100% will largely depend on your movement skills and consistency and choosing one route over another will not necessarily guarantee you a better time unless you are better able to execute that route.

Near the end of the run is a trick known as Glass Tube which, if done correctly, will save time by avoiding some extra backtracking and room transitions. If you fail the Glass Tube trick you can choose to accept the timeloss and backtrack to gather the Etank, or you can continue past the item on what's known as the "Old Route" before the glass tube trick was found. This isn't so much a route choice but more of a recovery option in a racing situation to minimize the timeloss from failing the trick.

One last major routing difference I will cover here for the sake of completeness is the HBJ route in Kraid's Area. This route will mainly be preferred in the Hard Mode version of this speedrun due to ammo differences, but it is still a viable route for Normal mode. The reason it's not included in the main list above is because it is much more difficult to execute this route optimally and there is hardly any time difference between this route and the much easier route in Normal Mode.

Brinstar

Every run will start off this way up to the Bombs item. After picking up the missiles behind Bombs is when you decide if you're going up to the Early Brinstar route, or back down for the Late Brinstar route.