Okay so I finally sat my butt down and played through this and I have to say it was really immersive, mainly because of how good the writing is! I have to say, MC is the most MC as they managed to even make their own self-doubt fall in "love" with them which I find absolutely hilarious. But I do have to say how interesting it is that each of Geist's words were so carefully picked out and targeted that even me, as a relatively less-overthinking kind of person, began to think about all the things Geist's says.
I like the use of the VAs, I know that there are realistically only two VAs because of the relevancy of Geist and Kalei but I like to think MC can only "hear" these two characters because of the amount of impact they have. Like, Geist's voice being all smooth and his tendency to enunciate words really makes you focus on him and his slow cadence, like he drowns out everything that you don't put in any audio in the background signifying the outside world because MC has gotten used to desperately trying to block out Geist's words that, by consequence, they've blocked and isolated themselves from hearing the outside world as well.
So, having Kalei able to speak helps ground MC, especially when it actually stops Geist from speaking because now MC's thinking isn't clouded over negative thoughts but focusing on Kalei. I also like the duality of their voices, Kalei noticeably has an accent but his voice is bright, fun, expressive, and he talks in a pretty chill manner compared to Geist's more formal way of speaking. He's the direct opposite to Geist which is another way to visually set them apart, and I think it helps ground MC because MC doesn't really notice anyone, nobody has any art or even a name attached to them aside from Kalei and Geist so having them visual different makes it so that MC can starkly recognize them (and also the Hawaii somewhat music playing every time Kalei is on scene is so funny, I wonder if MC's mind is just playing that as Kalei's theme).
I didn't think Geist is much of a yandere, he only really shows it somewhat at the ending where you have to push or accept him. I know that yanderes aren't ALWAYS violent, they manipulate and hurt you so you can stay by their side, and their love is both painful and suffocating. Looking back, I do think Geist was showing his love in a backhanded way by isolating MC and making them dependent by beating their self-esteem and identity all while spinning a nice story of accepting the version of MC he managed to create by ruining the MC that would have never created him (an MC with no self-loathing thoughts).
The yandere-ness is subtle but no less toxic and I find it very interesting how Geist mellowed out, he'll never fully be away from MC and even if Kalei is in the picture. But Kalei will never live inside of MC's mind like Geist is and I think that could be Geist's ultimate petty victory over Kalei. That in the end, he'll always will be by MC even if they don't want to acknowledge it, they'll accept it.