Complex sentence: Samsunspor had a tragic accident during the season, for that reason, they cannot play their last 18 matches and all these matches were awarded 3-0 default win for Samsunspor's opponents.
Split into simpler sentences: Samsunspor had a tragic accident during the season, for that reason, they were unable to play their last 18 matches. All these matches were awarded 3-0 default win for Samsunspor's opponents.