One of the things I think Lindsay also brings up is the importance of separating the language and the practice. I actually wonder if there's ever been any real discussion about, for lack of a better term, "game language". And I'm not talking about game design. Game design is about the rules and structures inherent to the creation of a play state (e.g., the difference between an FPS and an RPG relates to the systems). Game language would be more related to what the aesthetics and interactions tell you from an emotional standpoint. How does one elicit sadness through interaction? Because I don't think that's specific to a game's design (it, in the same way cinematography has an effect on film, is more tertiary to it).
It's obvious when games present language cinematically (e.g., how they sexualize a character using framing), because they're just using film language in that context. But how a video game actually uses the language of interactivity, seems utterly foreign in almost every game I've played, or at the very least it's incidental (or accidental) to everything else that's going on. I think Valkyrie Profile actually uses what I might say is something akin to proto game language when it uses mechanics to replicate the passage of time and how that passage of time is connected to power structures and decisions within the interactivity of characters (e.g., the connection of the player and characters to the interactions). But that's hard to describe in a way that's easy to replicate or explain to somebody (at least, right now, anyway). Indivisible copies the DESIGN of Valkyrie Profile (e.g., combat system, platforming), but it doesn't copy that's game's language. And even so, Valkyrie Profile's language only replicates that marching of time, but it still uses a more book-like language for its emotional beats. The sadness I feel at the death of a character in the game is not a result of my interactions with them, but a result of my investment in them from a perspective of reading about them (e.g., reading the text boxes associated with their arc). Games are the medium of interactivity, but the emotional praxis within games is, at present, largely outside of interactivity. Games like Papers Please or Getting Over It or Journey seem to have a stronger idea of what game language might look like - or a game like Demon's Souls, where your interactions are directly impacting the rest of the world and the core of the emotions you feel has more to do with the consequences of what you as an interactive being in that world bring to that world. That said though, I think the first game that I would say is genuinely aware of game language, is actually Kind Words. Because it uses interactivity in a way that provokes and even necessitates an emotional response.