wide-open

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houshdaranmail

Hello.
What is a wide-open game?

Quote:
Able to calculate with immense speed and precision and possessing wonderful technique, Morphy played a wide-open, attacking game that made little use of pawns.

(from Play winning Chess, by Yasser Seirawan)
There are a few senses for 'wide-open]. Which one applies?

Thanks in advance