I believe the best ones are "Laterna Magica" (magic lantern) and the "Black Light Theatre". There are various others with similar sounding names. We went to a show called "cats in Prague" - nothing to do with Andrew Lloyd Webber! It was a tiny theatre with people in black with cat hand puppets that danced over rooftops and the music reminded me of Pinky and Perky (if you're old enough to remember them!). An experience, but not a particularly good one.

Hi,

I am answering my own question here! but hopefullly it may be useful for others. Just returned from Prague andl I decided on the Image Theatre http://www.imagetheatre.cz just off Old Town square. I would highly recommend. I booked in advance on the internet - good job as it was full. Make sure you arrive 1/2 hour before to get a good seat.

The show which was on when we went was the "Black Box" which is a combination of black light theatre using modern dance and music., but it also interspered with comedy mine scenes. Very original. Cost 400 cz, about £10, well worth it.

Enjoy