Guild Wars 2

Remember the Halloween doors and Christmas gift boxes in the world? They were so fun because they were triggered by the players.
It would be nice if the idea will be repeated even outside of main festive days.
Make some resource scanner available to players and when they trigger it to find “excessive resources” some dragon minions will spawn and the player will need to fight them till the resource gathering is complete.
Basic, Medium and Advanced scanners will be used as consumable and the quantity of resources gather will be different and the time to defend it too plus the number of foes.

There’s a TON of events out there already that can only be triggered by players, I’m surprised you never stumbled onto any so far. Most of the escort quests are always started by players, do you think NPCs will just blindly stroll down a dangerous path without some sort of protection beforehand? These are maked with a glowing event orb above their head, and the usually turn to you for help saying something like “Hey could you help me?” to every passing player until one accepts and starts an event for everyone to participate.

Most event are triggered by players. Some through talking to a npc. And others are triggered by winning or losing a DE.

While other events are triggered by player interacting with the environment. Each play may not be aware that they contributed to the DE.

But I do agree that I would like to see smaller events (1-3 player events) triggered directly by the player.