Back in 2011, NYX Interactive acquired NextGen Gaming for an undisclosed sum.
In early 2018, Scientific Games completed the acquisition of NYX Gaming Group for $626 million.
NYX is more like a platform provider, but due to the recent integration of NYX into SG, the three names can be used interchangeably. To cut a long story short, if a certain casino has SG titles, you may rest assured it has NextGen and NYX titles, too.