Slot machines are definitely one of the most popular casino games, and their following has carried over as online casinos are introduced. The first slot machine, Liberty Bell, was released in 1899, and the times have changed a lot since then. With the Internet boom of the 1990s, land-based casinos turned to digital versions of their offerings, leading to the introduction of new and more unique content with online slots. The popularity of these alternatives continues to gain since slots are easy to learn, require no skill and offer a lot of entertainment. Despite their history of over more than a century, there are several popular themes that continue to take the forefront of the slot machine segment.

Space continues to capture the attention of everyone, and is featured prominently in online slot machines. There’s a huge number of space-themed slots available today, with their science-fiction takes on the otherworld and unique combinations that offer almost alien-like payouts. Some of the more popular slots in this category include Alien Spinvasion, Asteroids, Colossol Gems and Galactic Streak.

Adventure games are another popular category. For those who like adventure, there are some unique offerings at online casinos. Mr. Vegas by Betsoft is one. It combines a classic Vegas atmosphere with an adventure game that is different from the rest. Another is Betsoft’s Greedy Goblins. This is a 3D slot game that takes the player on a wild ride.

With sports being so popular around the world, it’s no surprise that sports-themed slot machines attract a lot of attention. There’s no shortage of options when it comes to sports slots, with games inspired by baseball, basketball, soccer, football and much more. For every sport fan, there is something that fits.

Fantasy games are also some of the most popular and they’re everywhere. The most common inspiration is found in fairy tales, mythical creatures and ancient mythology. More recently, superhero slots have been added to this category, as well.