Without a doubt, the worst game I have ever played has got to be the Megadrive/Genesis version of Sword of Sodan. Utter, unadulterated shizer-on-toast. And to quote from Wikipedia, which in itself is a strike against the merits of the site for allowing precious bandwidth to be used in immortalising such a turd, behold:
"...The game was known for being notoriously difficult with horrible controls on the Genesis. It was also very bloody and violent, despite the horrible graphics, especially since you could stab NPCs in their genitals. The Genesis version had enemies attacking from both directions, while in the original Amiga version, all enemies were on the right side. The Amiga version also had a voice making announcements at key points, such as "beware of traps" and "jump over barrels."..."