Gilgamesh? Easy! Simply complete FF7 5 times within 10 hours without saving it, kill Safer Sephy with Cloud only, equipped the Buster Sword and no materia, then beat FF5 within 5 hours and defeat both Gilgamesh and Ex-Death with a level-1 Bartz only. Then, of course, write to Square and they will be so impressed with your achievements that Gilgamesh will become unlockable in FF7.

Why are FF7's character graphics so bad?