Sorry, but this isn't an RPG or open world at all, so none of what you're saying applies here. For starters, you can't just "go after" someone. This isn't even about that. There’s a harem, but the game isn't about managing one. That’s exactly why you can't choose who the team members are.
This is an AVN based on actual renders, not sprites. I’m pointing this out because every tiny variation of the same event means creating multiple images to reflect the changes. With my current setup, a single image takes between 5 to 15 minutes to render, depending on the complexity. And that’s just render time, not the time it takes to build the scene before rendering it... Just to give you one example so you understand: in Normal Mode, the finish line arrival is contested between 4 characters, and any of them can take any of those top 4 spots. Probability math says there are 24 possible variations for 4 characters (4 x 3 x 2 x 1 = 24).
That scene in Safe Mode consists of 17 images (Kaoru and MC talking while the girls finish). This means I’d have to render over 400 images to reflect all 24 possibilities for that one scene (17 x 24 = 408). I might be able to cut it down a bit, but not by much; it’ll still be at least 300+ images... each taking over 5 minutes to render and double or triple that to create.
Of course it HAS to be linear. Because the competitions already have many non-linear elements. And the competitions are vital since, every so often, a character with poor performance will be wiped off the map. Someone is going to die, and right now even I don't know who it is because it depends on choices and RNG.
Any AVN that isn't a Sandbox is linear, and this one definitely isn't a Sandbox. I use the relationship system to add depth, but the game remains linear because I control the flow, not a free-trigger system or the player's whim. In a standard AVN, freedom is always an illusion. Some just hide that fact better than others.
A small sample of this "disguise" for linearity is what I did a while back with the scene between Vanessa and the MC. Not everyone saw it because it’s a conditional choice. To see the sex scene with Vanessa before the competition, the MC must first have a certain personality score; if they don't meet the requirement, they won't even know the scene exists because the choice doesn't appear. If they have the score, only then does the option to have sex with her (or not) show up. That’s as much as can be done to disguise linearity.