《牛津》play

[transitive, no passive, intransitive] to pretend to be or do something for fun

•  play something       Let's play pirates.

•  play at something     Let's play at pirates!

•  play at doing something     They were playing at being cowboys.

牛津词典告诉你，假装是某人，用play sb, play at sb, play at being sb.意思是相同的。