I feel the need to clarify that there is a difference between a linear game, and a game with only one path of progression.
Super Mario Bros has, for various reasons, become my go-to game for drop in console play. Yes, the original NES title "Super Mario Bros." I do not consider this a linear game. I consider the likes of Medal of Whatever: Borefighter to be a linear game.
This may sound like an oxymoron, but I'm going to give you some explanation as to why:
Mario never offers me freedom. I must go to the right. MUST - the game limits how far you can backtrack to the point where if something has moved off the left of the screen, it's gone forever. I can move up and down as much as I like, within the limitations of the mechanics, but there is no in-to or out-of the screen movement. For Anyone. That is quite important as well; I am stuck moving left and right, mostly right. My enemies are stuck moving (mostly) left and right, with left being the primary choice. Within this basic framework, the game is doing little more than presenting me an environment, hazards within that environment, and letting me work it out myself.
A prime example of just how NON-linear Super Mario Bros is is the infamous World 1-2 Warp Zone. You can beat that level, and indeed most underground levels, by running along the ceiling. This is a game where there is on the surface NO freedom for players to choose what they do, and you can LEAVE THE LEVEL and run along your status bar to bypass 90% of the hazards! That is BRILLIANT!
Compare that now to the joy of the SGWW genre. I am told by Generic Yank Twat that I have to press X in front of a door to make something interesting happen. It offers me a sweeping urban environment, yet won't let me into any building save the one the game decided is my objective. When I try to explore I am blocked by ankle-high walls that I cannot step over for some reason, or a piece of cardboard that can somehow withstand a 60mm grenade impact, or an invisible barrier that will insta-kill me five seconds after I pass through it if I don't turn back.
Super Mario Bros does not do this. There is nothing on the map that exists for the sake of looking nice. There are no platforms you cannot reach, no buildings you cannot enter, no power-ups you cannot collect. If you really want to take an obscure, potentially suicidal route through the level, you can. You might die because of your own poor judgement, but you won't die simply because that route is not part of the scripted course.
Finally, the linear master class of Spunkgargling differs from Super Mario Bros in another important way - At no point was control of Mario taken out of my hands. Linear games, especially Spunkgargle games, delight in taking the controller off the player and forcing them to watch some awesome pyrotechnics. They insist on denying us freedom of exploration, or even freedom to IGNORE THE SPECTACLE and they do so without any warning.
This isn't saying cutscenes are bad, or cutscenes are linear. However, a lifetime of gaming has taught me that a cutscene is what happens when Bowser is dropped into the lava. I defeat the boss, and my reward is a cutscene that explains what I have accomplished (or not), and sets me up for the next bout of gaming. Super Mario Bros does cutscenes very well, given its limited nature, and never have I felt they were contrived, or forced, or breaking my immersion or in any way lessening my enjoyment of the game. On the other hand, just about every "GIVE ME THAT CONTROLLER!" scene in your typical Linear Game has left me infuriated. Yes, that scripted event is very impressive BUT I DON'T CARE! I was BUSY, thank you very much, now return my fucking character to my fucking control!
This, really, is a triple-A fail on the part of game developers worldwide; they spend millions on producing a 3D-rendered game using machines with specs nobody twenty years ago could even imagine existing, and yet the games they produce are more restrictive and more linear than games that are now considered primitive by the standards of a mobile phone app.