I get what you're saying. But unless we want to argue for a new tag (possibly "kinetic-lite"?) this game is more kinetic than sandbox. If you boil it down to its core there is no player agency in this game (minus the NTR "bad endings" that get retconned anyway). That, to me, makes it a kinetic novel. Yeah you can sort of determine the order of the minor scenes but all major plot points are static and unchangeable.
The what ifs are all Kinetic one shots and this site doesn't really give side stories it's own page. I'm assuming the kinetic novel might be for those. Since those don't have the sandbox part.
I made a comment on the new tag discussion but, for now, the
definition of the "kinetic" tag is "when a a visual novel style game presents the player with no choices." Thus, if there is any choice (and I can't conceive a game having multiple endings without having any choices), it's not kinetic. I'm ok with both tags if, as I said before, there are two entities (I could say two "games", but a kinetic novel is not a game; therefore, I'm using "entities") like a 1.0 that's kinetic and, them, the dev decides to do a follow up that is sandbox (or even a multiple-choice visual novel; it could also be the opposite, but it's rarely the case). Even though, for the sake of the developer, I thing there should be two entries (that is, two threads), because, for example, I usually filter out kinetic novels... So, if the dev applies both in a game, he might limit his audience (or, if the tags are applied by moderators, they'll be limiting it for him).
As I said, I know there are many games that are ambiguous, but it would be unfeasible to use this rule consistently: it would be necessary "judges" for it case. So, it's better to use the "kinetic" only for the strictest sense kinetic novels (and this is even the rule posted in the link above).
Moreover, most games have kinetic parts (cut scenes, interludes, prologues, epilogues, etc.); if we start to add "kinetic" to every game that has something like that, the tag will become redundant, and strict sense kinetic novels will be undetected (for both lovers and haters).