I wouldn't consider Rovering to Sussex a sandbox type game. For reference, I always think of sandbox games as showing you a world map and letting you click around to different locations... and they make you do grindy quests repeatedly to raise stats. Plus they have quests that can only be done on certain days, forcing you to play several in-game
weeks to finish a single quest line. I play a few but cheat often because I don't want to waste hours of my life just to see a single new story scene.
Sussex is not like that at all. It has choices, but I haven't seen any repeat. There are quite a few girls and what you choose gets you closer to certain ones. Like one day where you get closer to a girl based on your choice between going to the gym, the library, or the coffee shop. Once you get a feel for the personality of the girl you are pursuing, the choices aren't that hard to make (usually). There are free roam sections but they are much smaller in scale than BaDik. It's more like choosing in what order you want to talk to the girls. The only grindy part of the game is that if you like
all the girls, you'll have to maintain a
lot of save games and make careful choices in each.
Thankfully there are really only two girls I like, and one's a closet slut so she's easy to pursue.

My only gripe about the game is there seems to be a lot of focus on piss-fetish, which I'm not too keen on. There's some of that in Young Again, but it feels like a lot more in Sussex. Consider that fair warning, or an endorsement if you're into it.