Let's talk Puzzle Chests (a.k.a. August Monthly Quest)
Since the Puzzle Chests were added a few days ago there have been a lot of questions in chat about what they are, what they look like, how to do them, etc. but no in-depth resource on the wiki/forum where you can send someone with questions. In this thread, I aim to change that.
Disclaimer: Some of this information may be flat-out wrong. I started off knowing as much about puzzle chests as anyone else who read the development logs (which is very little.) The following is what I've learned from others or tried to figure out on my own. If you find an error, let me know and I'll correct it while giving you complete credit for being more smarter than me.
Let's begin with the most common questions:
Q: What do the chests look like?
A: Puzzle chests look like a regular metal chest except that when you click them or hold Ctrl+Shift they show up as Puzzle Chest. See below for a picture.
Q: Where are they?
A: Anywhere. They're on every facet and can be in towns, dungeons, forests, etc. There are around 4,700 unique spawn locations.
Q: How often do they spawn? How long do they last before despawning?
IDK: Not 100% sure about either of those, so I don't want to spread misinformation by saying anything. Someone else should reply and answer this.
Q: What's the "puzzle" part about?
A: It's based on the board game Mastermind. This one uses 8 colors and 5 columns. This version also causes damage to your character each time you guess the code incorrectly. Yes, it can totally kill you.
Q: What's in the boooooooxxxx???
A: Go to any Public Moongate and select Custom Areas > Monthly Quest Display to have a look at the possible goodies. As far as I know, Gwyneth Paltrow's head is not in the loot table.
A dramatic reenactment of how it works:
A wild Puzzle Chest appears!
Double-click to open the puzzle interface
Oh no, you guessed incorrectly
NOTE: The feedback gump will close if you die, but you can still see the results in your journal.
Your previous guess will be displayed upon re-opening the puzzle
Upon successfully decoding the puzzle, the chest will open and you can loot. If the chest is closed it can be reopened again without doing the puzzle until it despawns. Solved chests can be opened and looted by anyone; not just the player who solved it.
Helpful things to know:
The amount of damage increases with the number of incorrect guesses. The damage can get high enough to kill you.
The chest will give hints about colors used in the code and which column the color is in. Given that this shows up under "Lockpicking Hint" I'm going to go ahead and assume the chance of getting hints and/or quality of hints is based on your lockpicking skill.
If you encounter a puzzle box that says it has been tampered with, that means someone else has already tried to solve the puzzle and failed. Other players' failed attempts increases the damage for everyone.
Have I mentioned that the boxes can kill you? Always keep Gift of Life up so you don't have to wander around looking for a place to resurrect.
Puzzles can be done while you are hidden. The damage from incorrect guesses will not reveal you.
According to a very reputable source (WafflesNCyanide, who is way more smarter than me) having a high level of Remove Trap skill reduces the amount of damage taken by a failed attempt.
Also according to the same person who is more smarter than me, higher lockpicking skill results in better hints regarding colors in the solution and their column placement. There's even a link- http://uo.stratics.com/content/misc/puzzle.shtml
It is possible to access the puzzle chest interface while another player is using it, though you will not see their previous guess in the window. Doing this is not very nice and will probably result in you both dying after a couple failed attempts, so you shouldn't do it.
Things I have no idea about:
The development log says "Luck is taken into account, as is lockpicking and remove traps" and I don't know what any of that means.
Remove Trap- My skill is quite low, so I'm not sure what it does for puzzle chests. Decreased damage, maybe? I'm open to theories.
*Update* See the Helpful things to know section
Luck- Increased chance at better loot? That would make sense as my Luck is quite low and so far I've gotten nothing good from puzzle chests.
Lockpicking- As stated above, I'm guessing this affects the lockpicking hints. If someone with super high lockpicking would like to chime in on whether you get more hints, that'd be useful. If someone with low/no lockpicking has done a chest- do you get any hints at all?
*Update* See the Helpful things to know section
I'd like to thank Dante, Kane, and Domino for inspiring this thread. Without them, it wouldn't have made any damn sense to write about a puzzle chest monthly quest that doesn't exist. Jesus, Frank... get it together.
I got my everlasting Lockpick from one, Gwen opened it for me 
Lately I have done several of them. Unfortunately with low luck, I have yet to find anything good in them. They are fun at least. I use a Cu-Sidhe to keep me healed and Gift of life.
Also the 30 seconds on invulnerability after death is wonderful for trying out several patterns fast without killing yourself.
