The idea of this contest is to be a re-envisioning of the Heads and Boss Heads contests with a heavy focus on death and puzzle elements.
Participation would be on a sign-up basis, like BHC had. Contestants will be given an item that unlocks the arena location. Upon entering the Murderball arena, the access item would be removed and replaced with a fast use killing implement (1 minute cool down). This killing tool also functions as the key to leaving the Murderball arena - a player may deposit it in the central scene to forfeit the contest and be automatically removed from the arena. Because this is a heavily combat focused contest, a player with a Creature Protection Shield is unable to participate (as this grants combat invulnerability)
For every competitor that a player kills, they will accrue on head. If a player has a bundle of heads, they may be attacked as per a normal heads contest to try and take their heads. If a player is carrying heads when they die, the accumulated heads are simply lost - they are not transferred to the killer, and the killer only gains the standard one head for the kill. Additionally, to ensure that people from all timezones can participate, every three hours players will gain 1 head.
Players who are killed during the contest are teleported to the central location, and revive after 30 minutes.
The purpose of the heads is to access puzzle stations. Each puzzle station requires a fixed number of heads to access, which must be payed each time the clickie is opened. Progress in puzzles can be saved before closing, so you can make multiple attempts to solve a puzzle, starting from where you left off each time. The only things that force a clickie to close without your consent are being killed or going idle. As you are teleported to the central location when killed, this will automatically force a refresh, which closes the clickie interface. Save your progress often!
The contest lasts until all puzzles are solved, or a set interval of time (for example, three days) has passed. The winner is determined by who completes all the puzzles first; failing that who has completed the most puzzles is the winner[s]; and if no puzzles are completed whoever has the most heads wins.
An example arena is illustrated below:
The entire arena will be a no jump zone, to prevent people taking the tool out of the arena. The only way to exit the arena is to deposit the killing tool at the exit clickie in the central scene.
Edit: Special thanks to Kyphis for helping me hash out ideas.