Just bought Puzzle Agent on Steam and currently playing it. However, I couldn't find a way to exit the game. I pressed ESC and many other keys, but nothing happens. I would expect ESC to trigger the a menu containing an option to exit the game. I did notice the SPACE bar can be used to pause the game.
I killed the game's process using the Windows Task Manager, but that can't be the normal way of exiting this game, can it?