Why create that confusion for new (and apparently not so new) players? Just let the multiplayer setting in the option menu do its job based on what the player sets it at, and just have the "New Game" button take you straight to character creation (while also removing the behind-the-scenes switching of your carefully selected setting in the process).
The option you mention should not even
be in the options before you start a game.. it should be an option when starting a new game, as you say. "New Game" and we should be asked whether SP or MP (and if MP, with what settings)
Does this mean a game started as Singleplayer / Offline can be turned into a MP game in-game? That'd be a HUGE scripting issue if campaign creators can not disable this.
Singleplayer needs to be a permanent setting or it
needs to be something campaign creators can enforce on their campaigns with variables. (Same for MP) Because scripts for a purely offline campaign and a "possible players drop in/out all the time" campaign are VASTLY different. ...
This isn't just a question of confusing players or taste. There are far reaching implications when a SP started campaign can not be trusted to always be SP
