Simplify the following text for a Grade 12 native English-speaking person.
Original: After becoming editor of Asimov 's , Dozois 's fiction output dwindled , but he is now making a comeback , with his 2006 novelette `` Counterfactual '' winning the Sidewise Award for best alternate-history short story .
Simplified: His 2006 novelette `` Counterfactual '' won the Sidewise Award for best alternate-history short story .