What really makes the game intriguing isn't the subject matter itself, although that is already pretty original. No, it's the fact that to play the game you'll need not just a keyboard and a mouse, but also a webcam and a microphone.
Using the webcam you'll have to lift up your shirt (yes you, the player) so that your avatar within the game (the prostitute) does the same and attracts clients. Meanwhile, you'll use the microphone to fake orgasms when you're with a client.
In other words, it's pretty normal that when playing LUPA you find yourself with your shirt half-off, shouting at the top of your lungs so that your character does a good job.
LUPA is a unique game in all aspects, and also has attractive 'pixel art' graphics. Even gameplay itself contains more than meets the eye.