Great Game and wish I had replied earlier. Not new to F95, but a new account after losing my old computer and info:
Few games can or have been so involved that all the plots, relationships and storyline tracks while still being a game. Summer Story almost writes itself. I just played the last version after a lot of frustration as a game should be.
I would encourage the DEVs to continue down their path but not to be in a rush and ruin what has already been established. Now that the "boss" is out of the way as a conflict tool trying to get into Kasie's panties, there still needs a conflict that further develops the relationship between Derek and or Kenny--without (sigh*) a worry of NTR content that sets off all those opposed to ntr (*sigh again). And introducing new characters may or may not work with the storyline. So, to keep plot foils going use those who have already been introduced.
We don't know much about Mia's boyfriend nor the two bullies who assaulted Kenny. But it would be easy to flesh out them in a limited fashion to get that conflict. Perhaps Mia could invite Kasie to a beach party (bonfire or not) were her boyfriend hits on Kasie and Derek comes to her rescue.
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Of all the characters that make this game work is Kasie. Most see Kasie as being rather passive, modest, shy at times, and reserve while her emotions cause her doubts. And since this game hits at realism, it's important not to flip her personality but give the reader insight to her inner conflicts. If she has a flaw, its she can be seduced. And I think it's been the seduction that has gotten the game a good following. To further Kasie's development, she will need to experience fear (like getting pregnant), worry about her own moral code self-image, and embarrassment being pitted against her own desires and lust. Since we have at least two scenes where she gives ins having made out with Derek.
So, if you had to rate where Kasie is at on a scale of 1 to 10, she would be a solid 6 as of the end of the latest update. Eventually, Kasie will have to transform from being acted on via seduction, to acting on her own desires. For example, Kasie would knowingly put herself in a position where she knows there is a risk of inviting Derek (and or Kenny) to make an advance on her. A good image to think on would be, for example Mia taking Kenny to a comic books shop leaving Derek and Kasie alone, and Kasie deliberately wears revealing clothes in the secret hope Derek makes a move on her. From there Kasie would progress to more boldness--perhaps waking up in the middle of the night seeing Kenny asleep or perhaps Kenny had fallen asleep in the Livingroom from binge game play and Kasie "wants to have a talk with Derek (whispering)" and becomes emotional to engage in another make out session. Where Kasie hits 10, it would be where she would rub Derek's groin as to start sex.
The real trick. Is not making Kasie from home spun goody, goody to raging slut monster. Things like BJs and HJs ought to be limited. Actually, with the flavor of this game, it's going to be rather difficult to get a good 3-some outcome that works within the game. In such a 3-some how the DEVs put it together ought to prove interesting with many possibilities like sloppy seconds or one Derek or Kenny starting off with oral while the other plays with Kasie's breasts and kisses her. As to the kissing scenes, I wish other developers would take note on how its rendered--some of the best art I've seen in these games.