Sixteen years later Elmer visited the Cannery Casino in Vegas and returned to the Megabucks game that had been so lucrative for him in the past. When Sherwin visited the Mirage Casino in Vegas for its 1989 opening, he managed to walk away with $4.6 million with $20 he borrowed from his wife at the time. This story takes place quite a while before the other stories of big wins and is the tale of a WWII veteran named Elmer Sherwin. Here it is then, our guide to the biggest slot game wins ever claimed in land-based casinos: 6. In fact one particular slot machine – Megabucks – has been responsible for every single winner on our list. Thanks to progressive jackpots, slot games have provided some of the biggest casino wins in history. Yet that could not be further from the truth. Assuming they are low stakes and thus provide low wins, many ignore them for high-paying table games like blackjack and poker. Slot games can often be overlooked by hardcore casino aficionados.