This post spoils Into, which is about 5-10 minutes to play. You should probably play it first, if you care about spoilers and such.
Ingmar Bergman's film Persona (1966) is about two people who kind of merge into each other. Maybe this happens because you share a lot of interests or temperaments, or you're in love, or you're family, or whatever. In Persona, this merging process is often difficult, confusing, awkward, and/or painful. It inevitably takes on sexual overtones, but this sex feels violent.
Into (2016), by Charle Taylor Elwonger (Animal Phase), pushes the opposite tone. It is a short "interactive" about two people who are kind of joining into one another, but the joining is not particularly unsettling. There's a risk to it, but it also feels right to take that risk. Why does it feel more right than wrong?
Let's think about how Persona makes "merging" with someone else feel wrong. One of the most famous shots in Persona is these two similar-looking women gazing into the camera -- their facial expressions and performances make it feel kind of unsettling. You could say it's because they're breaking the fourth wall or whatever ("are they implicating us, the audience?") but I think it's more about their intense eyes. They also have unequal height in the frame; the woman on the right is gripping the other woman's head, as if forcing her to look that way. There's an unequal power dynamic here. It doesn't seem entirely consensual.
Into dodges a lot of these unsettling features just by having its characters face away from the camera. We only get momentary glimpses of their eyes, so their relative lack of facial expression (humanoid 3D characters suffer from lifeless "uncanny valley" effect in general) doesn't really get a chance to jar us. Elwonger also positions the camera in between the two characters as they face away from us. We're part of their group, we're spatially aligned with them, and we roughly see what they see.
To reinforce this sense of shared perspective, there's some subtle screenspace textures overlayed onto the scene. Now we're not just looking at the same thing, but we also look at it in the same way, and see the same non-diegetic features and meanings. These characters never have to say something obvious like "I love you" or "I feel like I'm a part of you" or something (instead, they talk about other things) because that emotion is already established by the visuals and shared controls / player inputs.
This dynamic leads into the very well-executed ending sequence, when we're watching both characters face each other naked in a shower. Elwonger blurs the entire screen throughout this scene, which to me, made the scene feel hotter and steamier, but also feels kind of like a concession to this couple's privacy. We're not part of them, we can only watch.
At first, you assume they share the same camera and camera-space in the shower, because that's what the previous scenes have done -- but then they reach up to join hands... and their hands suddenly disappear, cut-off by an invisible screen split down the middle. The result is a mirror-like composition as they finally "merge" into each other. I actually found this a little unsettling and moved my mouse cursor a few times to make them hesitate and pause the process.
In the end, of course, you have no choice but to continue. But by letting me hesitate at all, I felt like it was saying, "this is good, but it's scary, so it's ok to go slow." Where Persona (and its grandchild Mulholland Drive) uses a lot of muddied plot chronology to reinforce the effects of losing yourself as a total loss of time, Into just wants to make time felt. It's ok to go slow.