Lessons From Bregenz V

MY round-five game, in which I was Black against Erich Kampenhuber (1675), reached the following position after six moves.

I have just played 6...d3!?

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My opponent almost instantly replied 7.exd3??, but felt obliged to resign after 7...Qf6.

The whole game took under 10 minutes, and ended with him rushing from the room, without signing scoresheets or resetting pieces.

LESSON: "Is it a trap?" should be one of the first thoughts to go through a player's mind when the opponent plays a move that seems to give up material for no good reason.