Slot games are the biggest type of casino game by far. The number of people who play them at land-based and online casinos comfortably exceeds that of any of the other games.

They have held on to their place in the public affections for a very long time. The first ever slot machine is thought to date back to 1894 and was the invention of one Charles Frey.

Called the Liberty Bell, it had most of the features we associate with the games to this day. Slot machines subsequently became a constant fixture in bars and arcades before making the move online in this century.

These days they are a casino game that that skews female, but what are the slots that have had the most success with casino customers over the years?

Rainbow Riches

This slot was created in 2006 by the company then known as Barcrest and is still available at most sites today. That long-term appeal in a sector as ultra-competitive as the online slots one is real proof of its classic status.

If you want further evidence though, look to the fact that it has spawned numerous sequels. These include Slingo Rainbow Riches and Rainbow Riches Drops of Gold.

All employ the same lively Irish theme, with a countryside setting, blue sky with rainbow, leprechaun and pots of gold. It is fun, if not exactly politically correct.

The series is so popular that a Rainbow Riches Casino was created where you can play the original slot machine online as well as the sequels.

Mega Moolah

Another slot that was produced in 2006 and is still on offer at casino sites is Mega Moolah. This one is the creation of the renowned company Microgaming and it was originally regarded by most as a challenge to the Mega Fortune slot.

It has an entertaining theme centered on the jungle, with graphics of lions, zebras and monkeys, but it is the progressive jackpot that really made its name. Those are the slot jackpots that keep building in size until someone wins.

Well, in 2015 someone did win Mega Moolah – figuratively and literally. Landing the jackpot for this slot brought the lucky winner around $21 million.

It made headlines around the world and supercharged the popularity of the game, which you can play at virtually all online or mobile casinos.


Although this IGN slot game debuted a bit more recently than the previous two, it has still been around for a decade. It remains very popular and both the original and the sequel can be found at pretty much every decent casino site.

Ancient Egypt is rather an overused theme in the world of slots, which makes the stand out popularity of Cleopatra all the more remarkable. It develops its theme well, with cool reel icons of Cleo, scarabs, pyramids and the Eye of Horus, in addition to Egyptian music.

Arguably the sequel has better graphics and also throws in a free spins feature, but both games qualify as enduring slot classics.

Wheel of Fortune

If you think the other games featured here are old, Wheel of Fortune puts them all in the shade for longevity. IGT launched it in 1996, making it one of the very first games to hit online casinos.

It was also one of the first to introduce themed slot games, being inspired by the hit TV game show of the same name. There have been different versions of it produced in the years since, which is another marker of its status, but the three-reel original remains the biggest.

It is another game with a progressive jackpot and has thus produced quite a few million-dollar winners over the years. That never hurts the popularity of a game.


Created by a leading online slot developer, NetEnt, this is another game that has stood the test of time. It first hit online casinos back in 2012 and has stayed a steady favorite of slot customers in the decade since then.

What is unusual is that Starburst does not really feature a whole lot of bells and whistles. It has a fixed number of pay lines, five reels and a simple theme based on different colored jewels.

It does come with some extra features, like a wild reel icon that can trigger free spins, but compared with more recent slots it can appear quite basic. Its ongoing status as a slot fan favorite has been attributed to just that though.

The thinking goes that it is the ideal game for new players to start with because it is so simple, backed up by its widespread availability at online casinos.

These five slots have been around for years and still bring customers to casino sites in 2023.