A little difficult to find, we walked around, tried the door indicated and it was locked. We were about to walk away when we tried the door ten metres away and it opened with a sign pointing downstairs to the actual arcade.
It's actually a bar with good priced beers and lots (40ish) of older arcade machines, the ones 50 year olds (me!) remember well. Packman era. We changed a couple of notes at the bar when ordering drinks and could have stayed there for hours. You find an old favourite. My daughter played Ms Pacman for the first time in her life and was plaesed to get 5000 points, my wife had a go, even my son had a go...then I showed them the old magic and first time got about 32000 points. The secret always was to forget the little pills and only eat the magic big pills when the four baddies were chasing you, then catch them when they are blue. Once learned never forgotten :)
If you just want a beer, loads of sofa's to sit at and you will be with locals, not tourists. GREAT FUN, highly recommended. Initially discovered on "HONEST PRAGUE" and their youtube videos are well worth watching before you go to Prague.