NetEnt is one of the oldest studios in online slots and produced several of the games that defined the format. Its catalogue is the closest thing the industry has to a set of standards — titles other studios were measured against for the best part of a decade.
Starburst is the most-played online slot ever made, and its design explains why: ten paylines paying both ways, expanding wilds with a respin, and no bonus round at all. Gonzo's Quest introduced the cascading avalanche with a rising multiplier, a mechanic now used across the whole industry.
At the other end, Dead or Alive 2 is one of the most volatile games in wide circulation, with a free-spins round that can run for a very long time or end immediately.
The NetEnt collection is a good place to see how the standard features of a modern slot — expanding wilds, cascades, sticky symbols — were originally put together. All games are free to play in your browser.