What you have is the barest bones of a plot...this is fine, but be aware in of itself it is neither good nor bad, it simply is what it is....a basic start. But....this is where everything begins - the initial idea or inception or moment of genius/madness. Where you go from here is what really matters. For example:
The Bad Guy ruled the world through mental domination of most of it's subjects. In the Bad Guy's dying throws his last act is to drive all of his subjects insane and thus the world you travel through is one of danger and illogical mayhem as you seek to return to the safety of your home...but will your home be one you recognise anymore.
OR
The Bad Guy being defeated has led to a power vacuum and various generals have taken action to secure their sectors and make bids for the ultimate job, in other places anarchy has broken loose as the civilian populace has overthrown the military leadership in their respective sectors. Thus creating a world in which the player might travel through a number of different areas each with their own political ideology.
OR
The Bad Guy has been defeated and as you make the journey home everything becomes more dangerous, more chaotic, more insane until you come to the disturbing conclusion that the dragon's magic is the true evil and the Bad Guy was simply a pawn. Which begs the question - was taking the dragons truly your choice or have you already succumbed to be the next Bad Guy?
OR
and the possibilities stretch on.
The reality is any idea (no matter how bad it might seem) can be made into a decent story - it just depends on how you do it. So is it good for basics? Yes...but whether it turns out to be a decent story is completely up to you (or your writer).
Hope this helps