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The closest I've found so far is Randomly Generated Quests; Repeatable Quests refer to quests that stay exactly the same.
Seconding Randomly Generated Quests
Red Faction: Guerrilla is a good example of these in an open-world game; at semi-random intervals the game spawns optional mini-objectives like enemy raids on friendly bases or convoys that could be disrupted, each giving small amounts of morale and funds, and occasionally minor benefits like temporarily reducing passive enemy spawns or whatever.
Edited by Scorpion451
Sometimes in open-world games, you get an alert of a small mission happening nearby. Usually it’s an NPC in danger or a criminal escaping. If you help out and complete the mission, you’ll get a reward (small amount of money, common rank gear, or maybe the happy feeling of helping someone in need.). If you don’t, the bad guy gets away and anyone in danger is dead. However these randomly occur at any time, so you get multiple chances to do these.
They aren’t specific side quests, as they usually only take like 3 minutes to complete