EuroGamer have taken a look at a rather unusual PC arcade-style shooter called Bacteria, which takes place entirely within a human body. You really need to read this to understand whats going on. Here's a little taster:
"One of Bacteria's strongpoints is undoubtedly its graphics, from the murky red backdrop of the scientist's veins and the floating platelets and blood cells within, to the impressive particle-driven weapon effects and the spectacular explosions they produce when your shots find their target. The bacteria themselves are nicely detailed and suitably outlandish, with thirty different species ranging from crab-like organisms and flatworms that slowly ripple their way through the blood stream to what looks suspiciously like a turtle."