metastage

The story in the metapuzzle makes references to two things: brooding, suggesting something to do with Brood War and trees referencing tech trees. In addition, the walls in the game form a giant T, suggesting Terran.

The entire puzzle hunt has been organised around the Brood War Terran tech tree. Each stage represents either a building or an add-on, and the numbering encodes the relationship in the tree.

For each level, the first digit was incremented if the building unlocked a further tier or units. The '.a' and '.b' levels corresponded to add-ons.

Since the Science Facility has two possible add-ons, all of the stages corresponding to add-ons were about a concept which had the 2-letter acronym to distinguish between them:

3.a (Machine Shop) - The ability belongs to the Mothership.
4.a (Control Tower) - The clue was spelt out in game using Creep Tumors.
5.a (Physics Lab) - SK Telecom T1 won the 2011-2012 ProLeague Season 1.
5.b (Covert Ops) - The puzzle involved players in the Community Opens.

The game being snake was just intended to be a fun way to deliver the puzzle string. Each item you pick up gives a hotkey, an associated colour, either blue (building) or violet (advanced building), and a point value (corresponding to the letter of the answer to take).

The sequence of pickups and the associated letter they contribute is thus as follows.

Thus the final answer is sniperridge. Checking this answer gives the final instruction and trivia question: "Who is The Terrorist behind all this who defeated the unused answer (3.0 Factory - Flash)?" The answer is Fantasy, who is known as "The Terrorist" for usage of vultures. This is also hinted at by your companion being concussed in an earlier stage (the vulture attack is concussive type).