Alternately, you could tell the player the exact location of the treasure, even mark it on their map, but leave a sleeping dragon/ogre/whatever on top of the treasure.
Player still has to travel to the treasure location, but taking the treasure is no longer "free", as they have to risk combat/use pickpocket/etc.
that's what it does now, but with only a 50% chance of being guarded. the idea being that guarded treasure is still there because its guarded, and unguarded treasure is still there because you're the first to ever find it (somewhat contrived).
if its always guarded, its no longer a MOVETO_QUEST (move to rumored treasure location), and becomes more or less identical to the ANIMAL_WITH_TREASURE_QUEST.
with the MOVETO quest, i was looking for something the player would want to MOVETO as a quest. treasure seemed the obvious choice. also, some caveman rewarding you for simply going to a location for no good reason made no sense. thus the rumor of great treasure was born - IE a reason for the player to WANT to go there. i added the 50% chance of it being defended to keep the player on their toes, as they'd never know which rumored treasures they went after might be guarded. its a quest generator, so they can get this type of quest again and again and again, along with the other 49 or so types of quests. and each time, it will be a different treasure in a different location, and possibly guarded by a different type of "monster". the quest encounter tables are terrain specific, there's about half a dozen tables as i recall, each with one to two dozen types of "monsters". quest locations, treasures, and monster types are all randomly generated.
and quest number appearing, quest treasure quantity, and quest treasure quality all scale to player level (party strength actually).
you see, i finally figured out what to do once you're high level - its not "what to do once.you're high level", its "whats left to do once you've done it all" - IE when you've run out of content!
the player needs a continual source of compelling new content appropriate for their level. in tabletop classic D&D, not that hard, given an obliging DM. in a computer game - a wee bit tougher. <g>.
the answer of course is the usual stuff, procedurally generated content, regular releases of new DLC, mods, user created maps / missions etc.
so for caveman the plan is questgens. i came up with ideas for about 50 so far. version 1.x had 16. i've already done 20, with this MOVETO quest being the only one thats not really ready to go yet. besides questgens, a simple quest scripting language and quest runner (mini VM) have been designed, allowing both user created and DLC quests. i plan to add quests as an encounter type that can happen with any caveman, not just at a band's shelter. hopefully the combo of lots of questgens, a game based on random encounters and random events (instead of hard coded spawn points and NPCs), and quest challenges and rewards that scale with player's level will help keep things fresh for long term high level play.