I do not think that we need to branch the entire game or even most of the game. Honestly, I think that most authors could get away with the last third/ final act of the game like choice of robots and/or magic.
Take Hearts of Battle. Massive spoilers:
This text will be blurred
The first two third of the game is fine. Then that scene happens with Ferrado and there is a marked shift in the quality of the game because once you get back from the trip and deal with the breakdown of the arena it feels like the game should branch.
Try to imagine it. A rebellion path with remi where you end up doing what the rebels seem to mostly always do in the game anyway, but now its a choice and you actually get properly involved with the rebellion Ferrado and the other noble should properly potentially die in this path.
An Eryx path where you continue working the showboasting in the arena, but it culmitnates in having to fight your lover. Oh no!
That is already where the author where going with Eryx, but it falls flat in all the cases where the mc does not get along with Eryx. Imagine instead if it only happened in their route and specifically because the overseers of saw that you were a couple and set the fight up to screw you over. Free romance drama right there in the text.
An a ferrado path where you try to game the system to become their bodyguard and have fun with the character Ferrado was untill the twitter discourse switch gets turned in their brain. The MC can flat out say that they are mostly interested manipulating Ferrado and that characteristic of the MC is another victim of Ferrados power imbalance obessession. But imagine instead that you got onto Ferrados final path by specifically saying that you want to play that manipulation game with them. Ferrado could keep their charactistation as someone dresses you in fine clothing and forced you to their parties, and readers would know that they entered an uneven relationship beforehand, and opt in instead of whatever weird twitter discourse.
Petra should properly have something to do with the flee branch. Two absued people who realise that “screw all this” we should just run. Would be a fine path.
I think people bring of Heart of Battle again and again because it is so close to being there. It´s author is good, the writing fits up til the last act, the potential is so clear and then… just nothing.
You do not even have to be that branching. Pirate Pleasure which most people agree feels more like a romance novel, does the smart thing and lock the ro just before the final conflict then the last act of the game is the mc and ro working together to deal with the mcguffin given the feeling that they are a couple now. It is not that much branching, but it does give each of the ro a time to shine together with the mc giving the reader a sense of “they are good together.”