This game doesn't seem to work very well in jsbeeb. In BBC mode it doesn't work at all, and in master mode it seems stuck in demo mode. Bugs have been raised to document this, jsbeeb issue 130 140 and 152. See also a discussion in the stardot forum, and another one here. The play button has been enabled to play it in BBC Master mode, which seems to work best, but it is probably best to download the disc image and play it in an emulator.