Gordon is a Sewer Rat who was recently kicked out by his mum and to survive in the world he's taken to scavenging for cheese. Fortunately, he's found huge chunks of the stuff just lying about the place but these cheddar-laden locations are roamed by Paddy the cat, Cecil the snake and a Tyrannosaurus Rex with the rather unlikely moniker of Bozo (who in their right mind would name a massive lizard after a clown is anybody's guess unless it was a larger and more ferocious example of the species) and contact with any patrolling beasts will all drain Gordon's life force until death ensues.
And if the local fauna wasn't enough to deal with, alien beings have invaded and (presumably they've cloned the locals since there can be multiple instances of each) and, if a pesky grey geezer should grab a wedge of cheesy goodness before our ratty hero can reach it, he'll immediately lose one of his precious lives regardless of remaining energy.
IT'S A RAT RACE AND YOU'RE CAUGHT
Gordon's world is presented in four colour mode 1 graphics and is a dark and forbidding place that is only occasionally enlivened by small splashes of yellow and huge pieces of cheese; the graphics themselves are unfortunately a weak mixture of hand drawn animations that are almost comical and some roughly converted images that look slightly out of place. The sound is also lacking, starting with a rather uninspired and plodding title tune and moving on to a couple of simple spot effects and occasional jingles during play.
Where Sewer Rat has major issues however is the level designs, some of which feel as if they've deliberately been arranged so that the player must immediately react in a certain way to avoid having most of their precious energy drained or to avoid watching helplessly as an alien legs it inexorably towards a piece of cheese and abducts it (the screens "Pipeworkx" and "Contact" are prime examples of each situations). And because there's a serious flaw which results in the collision detection being overly sensitive, navigating around obstacles leads to the poor rodent finding himself repeatedly "stuck" against the landscape despite it looking like he shouldn't be as a pursuer bears down on him; take a look at the second in-game screenshot and the gaps at the left are apparently wide enough for enemies to pass through but not Gordon.
Had the collisions been more generous and the movement patterns of the enemies a little less erratic, this could have been a far more enjoyable game but as it stands it'll take a degree of masochism on the part of the player to stick with it for any serious length of time.