FireLance said:Is there any way in which a solo game can be unbalanced?
I can think of two ways it might be "unbalanced".
One other folks have mentioned - the charcter can have more (or less) power than the GM is used to seeing, such that the GM has difficulty designing encounters.
The other way is to have power be very highly situational, so that a character's effectiveness varies wildly from one situation to the next. This is one reason why the "standard party of four" exists. Any individual may not be effective in a given encounter, but the party as a whole stays on an even keel in most situations.