I recently came up with a great idea for a plugin but also a server. The server i was thinking of making was a SFT(Sword fight tournament) in this server it would contain a plugin that has multiple arenas that cycle after every game randomly and the players would start with something like a wooden sword and no armour. If the user gets a kill then their "Kill counter" would go up one and they will be able to display their kills with /k or /kills, the kills act as a currency. There will be a sign shop inside of the server which becomes available after every round. Also, custom gamemodes of the sword fight tournament would be a possibility such as tdm, ffa, infection and maybe some other gamemodes. Thanks, Mozzie.
Have you check out my plugin BattleArena. Currently does all of that except for the currency (which you could always just use one of the money on kill plugins and buy ranks plugins to emulate)