Original: The player takes on the role of an engineer named Isaac Clarke, who battles a polymorphic, virus-like, alien infestation which turns humans into grotesque alien monsters called "Necromorphs", on board a stricken interstellar mining ship named the USG Ishimura.
Simplified: The player plays as an engineer named Isaac Clarke, who fights against an alien infestation which turns humans into monsters called "Necromorphs", on a mining ship in space named the USG Ishimura.