No. Έπαιξε, once in the past, simple past. "Was playing", imperfect, many times in the past. So, έπαιζε in Greek in this case.
Thank you pkaragoulis. I was wondering whether Ποιός έπαιξε might be ambiguous. If, for example, there were several things to choose from (i.e. games with masculine gender) and you were wondering which one he/she played, could you also say Ποιός έπαιξε? Thanks again. By the way, I love this site. Thanks to everyone who makes it possible!