DD10 was and still is totally like this. Drove her rule-following father nuts. For him, it didn't matter that she spent endless days happily playing with her game pieces - their purpose was to play that specific game and the game was wreaked if its cupcake game pieces ended up baked in her kitchen.
But it seems to be very much how she expresses her creativity. For instance, she loves arts of all kinds, but won't take a class where she has to reproduce a specific pre-defined product, whether it's a painting, ceramics or musical theatre. She will only participate in activities where she is given tools and techniques, but can use them to create whatever she wants. Doesn't make life the easiest(!), but it seems to be a deep and utterly consistent streak in her since she was a baby.
The best we have been able to do is make sure she does understand the rules and how other people use them, and the importance of agreeing with others on what rules will be used, when. To be honest though, while she can play a heavily structured game, she mostly just avoids activities that don't allow for a pretty significant amount of open-ended interpretation of what could happen next. Imaginary play remains a big deal for this one.
