IGT is the old giant of this business. They were building the physical cabinets on Vegas casino floors long before online slots existed, and a lot of their online catalogue is those exact machines rebuilt for a browser, which is why so many of these titles will look familiar even if you have never played online before.
That land-based heritage gives the games a very specific feel. Expect classic Vegas themes, Asian fortune slots, and straightforward old-school mechanics you will understand after a single spin. A tip before you play: always check the return on an IGT game. Coming from the physical casino world, they often release several different maths models for the same title, and the figures run anywhere from the high 80s up to nearly 98%, while max wins span from a modest 100x your stake up to 50,000x.