I know playing and building up on established servers is fun, but there's a certain thrill to exploring new areas, looting new temples/fortresses/villages/etc., and fighting your way through objectives rather than just autofarming it up.

So why not implement this as an event?

I'm not entirely sure if this is possible, but what I'm imagining is actually opening up an entire new MC world for the event. Not a permanent world, only existent for a few hours.

That world will be set permanently to adventure mode. No building, no mining, ONLY looting and exploring. And that's the point. Because based on how much loot a person can find in those few hours, they'll receive points (for example, name tags are worth x points, Notch apples are worth y points, etc.) and whoever earns the most points wins.

Players will have the opportunity to bring certain items in, such as a set of armor, weapons, tools, potions, etc. They will also be allowed to attempt to access the Nether and the End, though without the ability to build this will require some out-of-the-box thinking.

How it will be scored: At the end of the event, each player will have to place all their loot into a chest. They will get to keep their loot afterwards (as part of the fun), but only that which is in the chest will be counted. Obviously, harder-to-obtain items will be scored much higher.

This probably will need extra tweaking, because it's still an infant idea, but here it is for the taking. I would really enjoy being able to try this event, if it's feasible.

A bit late to the reply, but here we go.

I realize that some players like the "starting anew" part of the game, which was one of my goals with UHC: you get a brand new world every month, nothing on you, and you need to accomplish a set of objectives before the time is up.

I could see something in adventure mode working for a limited duration, if people had the target of finding specific items or loot. I'm not sure if allowing people to bring in items would be a good idea, though: that gives more powerful players an edge on the others, possibly breaking the balance between everyone.