Far, far in the future, the sun grew old and faint so man had no choice but to burrow into the earth's core in search of heat.

As they went deeper and deeper, they left machines to guard the levels etc, etc and etc. Miss out the next bit about a ship leaving to colonize etc only machines left etc and finally the crux of the matter. Yes, you once again are called to do your duty in the name of the human race, and return to your old planet Earth to destroy the machines your predecessors kindly left for you.

In this horizontal scrolling shoot 'em up you have what is termed a one-off 'total aggression' machine that, as well as having the standard photon cannon, has an interesting device known as a transmuter. This sucks up raw energy and converts it into extra speed or faster bullets. The more ships/tanks you blast, the more chance you have of making your ship more powerful.

This technique, if I am not mistaken, is a borrowed' idea that has first surfaced in Thalamus' Delta, albeit in a slightly different form.

I must say I enjoyed Transmuter, although it does have one or two really tedious moments like the long wait from end to start-up again. Also no matter how far you have ventured in, if you get blown up you start again from the very beginning. Not nice. That apart it's a good zapper that doesn't take much brainpower.

Despite some boring moments this is generally a pretty reasonable shoot-em-up.