This post is crap.
>Literature has the ability to put you directly into someone else's experience that you can't get from the other two.
>Film is purely observational but allows the artist to construct particular images which themselves can communicate things to the audience.
You should differentiate your definitions a bit more. I could easily claim that Literature is also just observational, and that "being put directly into someone else's experience" is only applicable to 1st person narratives, if at all, since often the first person narrator tells us a story. We are not put into a narrative but rather told a narrative. (Stream of consciousness being an exception here)
Just as we participate in the thoughts and stories through words, we participate in thoughts and stories through images. The distinction is finer, not this easy to make.
>The central aspect that makes games different is their ability to allow the audience agency in a story.
Very narrow definition, that seems, based on the games you've chosen, apply to yourself. A video game doesn't need a story, and also it doesn't need agency within a narrative. It can offer this, but there are also books that offer this.
> I think we have yet to see a DW Griffith emerge.
This shows a misunderstanding of why Griffith was so important, and also of what is the most fundamental capability of video games. Film's fundamental capability is to show movement. A Video Games fundamental capability is to allow you to interact within virtual reality, however it is defined or functions, which very often is very, very different from our reality (See for example a game like Defcon, Pong etc.). If we could not interact with it, it would be anything but a game. It gets a bit more complicated, what differentiates a video game from a general computer program is the second aspect, one that is very advanced and complex: It is a game. Now what a game is, what playing is, is an incredibly complex topic, and one i can not easily answer now. But i think you get the idea when i ascribe to vidya the fundamental capability that the player can interact with what is computed.
I find it nuts that people refuse video games the status of art. Look at pottery of the mycanean age, and good luck telling anyone that this isn't art. Now play something like Ico or SotC. What is created there is without precedent. Of course this doesn't mean that all vidya is art, but the distinction is almost impossible. Bethesda's games could be easily critisized for having low-effort story, quests, mechanics, visuals and so on. The world design, anything but handcrafted, filled with constantly repetetive 3d objects is lazy and sterile. At the same time they offer an unrivaveld interactivity, you can interact with almost any object, can manipulate them, you can steal, kill, travel, explore, fight and so on. Same goes for a game like Mountain Blade. That's unique, new and exciting, and offers a glimpse at things to come.