The online casino games with the largest prize pools tend to be progressive jackpot slot machines. These games can only be played if you are over the age of 18 (in most countries anyway), plus you can only play for a jackpot in the real cash mode once you have registered a real cash account with an online casino.
To be in with a chance of winning a progressive jackpot, you will need to launch the game in the real cash mode and you generally need to be playing with the full amount of paylines active per spin. Therefore if the slot has 25 winning paylines, you should play with all 25 paylines active per spin because certain bonus rounds can only be triggered when all paylines have been activated.
Some jackpots can only be won when five of the same jackpot symbols appear on a certain payline. For example, a Playtech slot called Beach Life will only award the top prize when five of the jackpot symbols appear along payline 20. This is why you should always play with the full amount of paylines active per spin and this is a standard rule with many of today's progressive jackpot slots.
There is a fantastic Playtech slot called Gladiator Jackpot which frequently has a huge prize pool. At the time of writing, real cash players can play on this slot for a top prize that is now worth more than £1.5 million.
Each time you (or any other player) takes a spin on a progressive jackpot slot, a small percentage of that stake will be added towards the main pot and most of today's progressive slots are connected to a major network of online casinos. This means that you can play for the very same jackpot at more than one online casino.
Mega Moolah for example, which is a Microgaming slot, can be found at approximately 150 different online casinos. These progressive jackpot networks basically allow millions of players to play for the same jackpots on a daily basis and this is why the prize pools can climb so high in such a short space of time.
There was one lucky player who managed to win the jackpot for a NetEnt slot called Mega Fortune back in January 2013 when it had reached as much as €17.8 million. Less than five months later (in May 2013) the prize pool for that very same slot has already climbed back up to more than €4.1 million.
Another software company that have developed a string of progressive jackpot slots is Realtime Gaming and one of their more recently released progressive jackpots slots is a branded video slot called The Three Stooges. The RTG jackpots may not reach as much as the Microgaming, Playtech or Netent jackpots can reach, but you can always guarantee that there are at least 25+ different jackpots up for grabs.
There are literally hundreds of progressive jackpot slots out there today and the great thing is that players can generally choose which currency they would prefer to play in when playing on these games.