Can't really think of any times I've played a game that had both single and multiplayer modes that I'd honestly believe the two were actually the same game.
It's generally a bad idea to try and mechanically span both single and multiplayer games with one system. Similar's fine, but they're just two different game play styles no matter how much they'll ever have in common and will need wholly different mechanics in places. Might as well just sell them separate from one another or pick one on purchase and unlock the other as downloadable content if you really have an interest in both.
As for those games which have an obvious preference as to which they are, they should just focus whole-heartedly on it and either toss the other or work on it as a separate game or an upgrade option for later. The development costs and times alone would probably cut ten or twenty off the sale price and whole months from the release date.
It's generally a bad idea to try and mechanically span both single and multiplayer games with one system. Similar's fine, but they're just two different game play styles no matter how much they'll ever have in common and will need wholly different mechanics in places. Might as well just sell them separate from one another or pick one on purchase and unlock the other as downloadable content if you really have an interest in both.
As for those games which have an obvious preference as to which they are, they should just focus whole-heartedly on it and either toss the other or work on it as a separate game or an upgrade option for later. The development costs and times alone would probably cut ten or twenty off the sale price and whole months from the release date.