Guildwars 2 used to (I assume they still do) just have it as a pop up, treasure chest "button" on each participating player's HUD rather than an object in game. Neverwinter Online has a box at the end of each dungeon, often next to the handy exit portal, that can only be opened if you entered during "dungeon hour" (occurs every 6 hours) or if you brought a dungeon key with you.
You can get one free key a day provided you don't already have one in your inventory. As a typical F2P opportunity you can also buy said keys with the pseudo-real currency of Astral Diamonds (which you gain through real money expense or through doing in-game tasks). Some dungeons and skirmishes even have two chests with the bonus one requiring a different key made from other grindable currencies.
Ultima Online laughs at treasure chests when bosses can just explode into gold.
Then there's Warframe and its Orokin Vaults. Found on not so accessible Orokin Derelicts that consume a crafted key just to ENTER, there is always ONE vault hidden somewhere in the decaying space craft and if there's something Warframe is good at, it is hiding things in hard to reach spots that require good eyes and good parkour skills.
The vault itself needs a key to open but the type needed is random out of four. Since each player can only carry one key at a time this usually means to have a 100% chance of opening the room each member in a full squad needs to be carrying one. Of course holding a key negatively affects your Warframe, depending on the type you carry.
The effects to choose from are:
-75% health
-75% shield
-75% damage
-50% speed
Upon opening the door whoever used up the key is back to normal, for a short time at least because picking up the always single "mysterious artifact" (which you will only identify at the end of the mission) will again inflict one of those four effects on you at random.
Oh, and it also triggers an alarm that changes your enemies into the Corrupted faction, so if you came in geared up to fight things with fangs, claws and tentacles you will suddenly find them joined by heavily armored folks with lasers, heavy machine guns and rocket launchers. I suppose I should mention that while not as creepy as the Eris Hive ships these derelicts are far more dangerous, boasting some of the toughest foes and traps in the game.
Vault looting is completely optional though, which means to -earn- whatever it is you looted you MUST complete whatever your actual mission is on that space ship AND make it to the extraction point afterwards. Alive. Specifically the guy carrying the artifact.
So far I've done two of these and they were awesome as it felt we really "earned" that extra reward. I've run many more where I was the sole key carrier and the vault lock didn't match what I carried though. Those were slightly annoying! :P
What's your favourite method of loot delivery in game? Do you like having an easy exit at the end or would you prefer that people had to "get to extraction" on their own?
