Credit to William1975 for giving me this idea (sorry if im not meant to mention ingame names)...
...alot of players prefere to go solo for farming, or to go solo with just AI. So it can get annoying when you enter a town or outpost and your flooded with invites to join groups.
So why not add a button to the party bar, to the right of the HM and NM icons which says "Soloing".
You select it and when ever somone goes to invite you, they get a message back saying...
"This adventurer has chosen to go it alone! They do not wish to join teams!"
...then your invite is cancelled and never sent. The solo player isnt interupted or bothered, and it saves wasting the other players time of asking them to join.
Maybe even add an icon above their head to indicate them going solo (no inuendos please).
f

