play at

verb4

1. •
   To pretend to be a different person while playing a game.

   • So we played at being pirates for a while.
2. •
   Used to suggest that someone is doing something very wrong, or incorrectly, usually with the possibility of causing damage or harm.

   • Hey! Stop throwing stones at the swans! What on earth do you think you're playing at?
3. •
   To do something in a manner that lacks seriousness, commitment, or professionalism.

   • In my opinion, John only plays at being an author. He hasn't sold more than two magazine articles in as many months.
4. •
   (no longer used) To play (a game).