Metroid Fusion is the 4th installment in the Metroid series of games (not counting the Prime games) released in 2002 as the sequel to Super Metroid.
Samus encounters a dangerous virus known as X, in which it can completely take over a living organism and mutate it. Samus after being infected has her power-suit surgically removed and is given a vaccine made from the cells from the baby Metroid she saved back on planet SR388. This makes her immune to the X virus, but something goes wrong at BSL station where parts of her powersuit were sent for examination. Samus, now with Metroid DNA, goes off to investigate the situation at BSL station.
This run by
Reseren makes use of a save corruption glitch that puts Samus right before the end of the game.