The concept is that it will be a RP in the modern days where there is a bunch of players who plays with a gm and many of those players when they hear a situation in this RPG says "I kill them all" or "I bash them and I capture them and I discuss with them with an upper hand" and many other violent reaction.
The players joining this rp choose what their human do freely and the players discuss the actual situation in addition there is some npc who are the main murder hobo players (Except if there is many players having chosen the role of a murder hobo).
Roles for players:
The GM(We need one and only one also at the end of a campaign he can change of rpg and he also choose the initial rpg)
Players.(It can be anybody but I discourage people under 3 years and people of four years are going to have an hard time understanding the rules of the Rpg(uo could even be a brother of the gm))
People on internet with which players can communicate but which will not play.(for example it could be a mad optimizer who made tons of theoretic optimization and post on forums or it could be the brother of one of the players(Who took some holidays at another place))
If a player does not posts it means that he simply had to do things independent of the rpg.
I discourage more than seven imbrication of rpg in rpg.