Usually, enemies in video games will attack on sight, as they're programmed to see the protagonist as an immediate threat, but this isn't always the case, as some enemies have to spot the player before engaging or won't even begin an assault at all unless given a reason to. Passive enemies in games can be applied to the "don't poke the bear" metaphor, so if the player doesn't hurt them, get too close, or otherwise provoke them, these foes will sense no danger and, therefore, won't feel the need to defend themselves.