Nex Machina is the (almost) official follow-up to Robotron: 2084 or, as I like to call it, the greatest arcade game ever created. If you watch the credits you will see the Eugene Jarvis was the creative consultant for the game. As far as I'm concerned that means this is Robotron: 2085 (we'll ignore Smash T.V. ... NOT canon!).
It's just as frantic and twitchy as ever, and the core game play remains the same: shoot everything that moves and save the humans. There is a far greater variety of enemies, boss battles, and the graphic effects are stellar. Improvements include lots of hidden collectibles, a variety of secondary weapons, the ability to dodge, and lots of differing level designs.