ZPF is definitely a shoot 'em up worth taking a closer look at. Technically speaking, it's very impressive, and had it been released on the Mega Drive during the console's heyday, we'd probably have mentioned it in the same breath as classics like Galenancer, Thunder Force and Truxton. It gets most things right and really only falls short in that there is sometimes a bit too much happening on screen at once, and that the game's wildly varied environments don't quite give it a sense of cohesion. But with its satisfying upgrade system and a highly customisable difficulty level, it's a must-have for any shoot 'em up fanatic's collection.