I love the more challenging chests like the Grog one and the Sorrow and I had a concept I thought would be fun and rewarding.
You could have a chest called the Siren's Call and every so often it sings and when it does it sends out a short ping during the song that marks your location on the map that other ships can see (to help with the pvp aspect) and it's worth $1000+ gold if turned in.
I like this one, but for the PvP'ers that get said chest, dependant on the mind set of the rest of that session, ie if the rest are PvE'ers just doing their thing, they'll be able to see exactly where you are to avoid you.
Only in said mentioned scenario, the chest wouldn't be all that risky and too high of a reward gold wise. More risky for the PvE'ers to have on board though.
As I'm typing this, as much as I like reading new chest ideas, it's sprung to mind that it could be used to troll/bait you into a trap, if that trap fails then sure.. Thanks for the reward ha
I had a few ideas for chest's too.
Obnoxious chest- this chest starts blabbing nonsense and can be heard at a distance( example: unhand me ya filthy pirates, i hope you all get scurvyyyy, you call this a crew? I bet davy jones wouldn't take the lotta ya). He could have contextual dialog for moments where you crash your ship or other moments.
Deadly grog chest- a poisonous chest that also makes you drunk, it could even attract the attention of the snakes around the island making them seek you out and attack you.
Ominous cloud chest- basically like your idea, but just a cloud that appeard over your ship. Other players could see it and know you have loot.
I would also like the devs to add special skulls.
