While it saddens me that you might not like the game, you're indeed entitled to your opinion!
If you don't mind I shall try to adress your main concerns whereby possible
What's with the 2 different colors & textures of hair co-existing on the girl's head?
The root of the hair is usually degraded over time unless the woman is dying her hair quite constantly, also as the Sun damages the hair it it's natural that ome shades of it shall be slightly different, therefore it was done as a slightly immersive thing!
I gave up shortly after they ordered the ham & watermelon.
As commented a few posts before you, the protagonists do so as an emotional thing. They acknowledge how terrible it is but it reminds them of their childhood so it's done for nostalgia!
Besides, it's not particullarly bad. It's a funky flavour
It is a shame that we wont have you with us for the future, but otherwise I hope you do find a game that catters to your tastes
Have a good day!
The ubiquitous lack of periods at the end of sentences was painful. I went into the source code almost immediately and mass-edited most of them in with a regex; if I'd lacked the technical capability to do this, I'm afraid I probably wouldn't have bothered continuing past the point where you meet her. (English not being your native language doesn't give you a pass on this one. Estoy bastante seguro de que el español tiene la misma convención de puntuación en estes contextos.)
The characters constantly address each other by the relations you define for them, rather than by their names; the latter would ordinarily be more natural in English (regardless of whether that relation is 'roommate' or 'brother/sister'), which may be why the preceding commenter thinks it was translated from Japanese. You do get points for properly [lowercasing!l] these in running text, though, which far too few authors do.
The use of Kimi wo Nosete (2.mp3) was distracting, and not really appropriate to the situation.
The boobs are excellent. Don't change them at all.
The lack of periods are mostly intentional to represent how the conversation goes on, and on, when periods are used it's to emphasize the ending! It's a common trope in a few surreal novels from the 20 century, but I do understand you personally may dislike it so for this I apologise!
Regarding her calling you "Brother" more often than simply your name.
You're right in saying that indeed in English it's a bit unnatural but frankly. It's a bit of a fetish of mine
Knowing the reassurance of their relation is what gets me going and for the conversations i've had with my fellow perverts, we tend to agree!
The main focus of the game, after all, is that you're shagging your little sister specifically
I am glad you did like the boobs, we do not plan to change them at all so I hope they keep you coming!
Thank you for your valuable feedback, do have a pleasant day!