Sandbox or Not?

 

The Scene: Yesterday's Game - D&D 3.5

Average party level 7th (ish)

Player joins the game who was not present at the start of the current scenario

New Player: "Who can I play? I didn't bring many of my character sheets"

DM: "I run Sandbox D&D. Bring whoever you like who is in town."

New Player: "Keeper of the Campaign Timeline, who do I have in town at the time of this adventure?"

Keeper (that's me): "Well....there's Dude X. He's in town at the moment, at a loose end."

It turns out New Player has Dude X's character sheet.

Dude X is 14th level.

DM (starts to shift uneasily in his seat): "Um....he might be a bit....overpowered....."