Every enemy gives you a Game Over in different circumstances. For most characters you meet in the first location the Game Over is possible if you lose three times to them and lose all willpower, which you can also gain in some ways. Other characters give you a Game Over if you fight and lose (Naga, Fire Elemental, Dark Knight). You have to beat the Dark Knight for real if you meet her in the second location.
In Patreon version of the game there's a cheat mode that lets you continue playing even after you got a Game Over.
