Other expressive mediums are limited in their ability to...
Video Games Are Art
You've certainly done a fine job defending video games as art... off the wrong definition. You have essentially equated artistic expression in video games to the mechanical process of creation akin to a book you'd buy called "The Art of Cooking" to help teach you how to make food. I am explicitly talking about art by the definition of expressing the imagination and abstract ideas through the form of artistic mediums such as music, movies, and novels. These are two completely different definitions and while, yes, video games are "art" in the way you describe it, that definition is no different than words such as "method", "process", "how to", and more - nothing about expression, but everything about objectively instructing you on how to get a job done. If anything you have demonstrated that video games are art through the intensive level of labor, care, and skill that goes into ensuring that every part works and makes sense - which helps reinforce my first point, surprisingly. What ultimately discredits video games as being considered an artistic medium is the fact that the elements which make a given game "artistic" in the eyes of many are elements which do not belong to video games exclusively. Not only that, but the one element that sets video games apart from other mediums carries little to no expressive opportunity. Take music, for example. It claims sound as its own unique trait for expression while vocalists write lyrics to help create a story to accompany a piece. Here we see how music and writing come together to create an artistic piece. However, music does not explicitly require a vocalist or lyrics to be expressive and artistic - as sound from instruments alone can construct entire narratives, worlds, and emotions on noise alone. For another example, film has visual movement as its own unique element. And while most films will be found including story or a soundtrack to tie those moving images together, film can express abstract ideas through camera angles, shot composition, and color. Other expressive mediums are limited in their ability to do this, as they do not have the privilege of tangible movement in their mediums. As for video games, the one element that sets games apart from other mediums is player input and control. In lets say, an adventure game, you manipulate the movement of the game's main character to navigate levels and get to the end of a game. Your own method of playing and experience, depending on the game, can change dramatically from how another person played the game due to our own unique inputs manipulating the end result of the said game. And unfortunately, that is all that video games can claim as their own unique element. Video games, especially those which many prop up as examples that the medium has artistic value, rely heavily on visuals, sound, and story to present abstract ideas and concepts since, simply put, there isn't a lot you can get out of expecting a play to press the X button at a certain point in a game. Ultimately, we praise video games on merits that video games do not claim as their own. And unlike a film where music and writing can service moving imagery to improve the meaning its creating - sound, writing, and visuals cannot service player control to enhance expression. It is the other away around. You have given credit to an aspect of video games that we, as audiences, cannot even see. The process of coding and design is skill and work that ultimately dooms video games as being accepted as an art form because, when discounting the elements of sound, imagery, and writing which are not exclusive to video games, it implies that video games can only be appreciated through a very objectively done job that audiences aren't aware of or don't even care for. Meanwhile, their appreciation is handed out to aspects of a game that you can easily find by picking up a book or watching a movie. Such as the Metal Gear Solid franchise, where eventually, the amount of cut scenes and scripted in-game events that map out each game in the series found itself being longer and overshadowing the gameplay itself. Yet you will never see anyone talk about how the gameplay itself helped cement the massive amount of themes and ideas that Kojima built up in his magnum opus. There are a few games I'd consider capable of presenting the element of player input and control as something of artistic value, instead of being there by obligation as a game to instead prop up elements borrowed from other mediums. Games such as Undertale and Hotline Miami, which use long established conventions in video games to deliver interesting stories and criticisms of the said conventions they borrow, deconstruct the nature of player control and movement by heavily breaking down the confides of their own games. Undertale emphasizes 'consequences by our actions' with a system that tracks the actions you made across multiple playthroughs and eventually, and mind the spoilers, finds your player killing the game's files themselves if you stray too far down a morally dark path - a method that has never really been seen before in a game. Hotline Miami, on the other hand, delivers a criticism on violence in video games and the pointlessness of delivering a moral in a game that would rather occupy your time with 'no questions asked' violence. The game structuring itself as a combo heavy, violent, and neon-hazy shoot them up plays into the story of a game that asks you important questions about what you're doing and why... and then eventually mocks you for trying to figure it out when clearly you were just there for the few hours of violent thrill. Other games such as Portal and even BioShock, too find themselves using elements of player control to create stories with very important and poignant morals that otherwise would not have any effect if told through other mediums. Yet, not only are these examples only a few out of thousands upon thousands of games. They are also rarely, if ever, included in discussions for games that "prove" that games are art. On top of that, nearly every single one of them when discounting Portal can only ever seem to deconstruct or criticize long standing elements of games that ironically limit video games ability to do far more on its own unique merits. Which brings games back to square one in showing that, as an art form, they are entirely limited or incapable of showing expressive meaning and artistic merits without borrowing elements from other mediums and almost always playing those said elements straight without player input contributing to them... or vice versa. To summarize basically. The most appreciated qualities in games being propped up as artistic are qualities that are exclusive to other mediums and are borrowed for video games. The merits of player control that video games claim as their own unique quality are either extremely limited or incapable of enhancing the elements video games borrow to create more amazing and expressive themes and ideas. The few games I provided examples for as being undoubtedly artistic could only ever deconstruct and call fact to the limited nature of video games and artistic expression, which hilariously puts them back at square one for proving games can be an art form.