Wow, this was... surprisingly good.
I'll be honest, I picked this up out of equal parts boredom and curiosity. The renders look great and it intrigued me that the main differentiating factor is that the story revolves around the grandmother rather than the mother or sister as tends to be the case in these games.
GILF stuff tends to be very hit or miss due to massive levels of subjectivity around the "ILF" part of the classification, and has not really been a genre that has drawn my attention in the past.
That said, I can unequivocally state that Grandmother's House not only sticks the landing but goes back for another round and nails that too.
As anyone can see, the renders are gorgeous, and their quality is well matched by the characterization and writing. While there is definitely a not insignificant level of "porn logic" causing every woman you meet to be attractive and attracted to the main character, there is enough going on in the story and enough depth to the characters that it's relatively easy to suspend your disbelief.
On top of all this, I have to give special praise to the diversity of characters, particularly fuckable characters, in this story. The spectrum isn't full, of course, but there is solid variety in appearance, history, relationship, and personality on display with all the women you meet. Sure, not everyone will be into all the characters, but I'd bet that everyone could find at least one character they will be quite attracted to, a statement that's rather rare given how frequently games tend to focus around one general appearance/characterization with minor differences.
At time of writing this game still is quite early in development, featuring only a handful of full sex scenes (and plenty of blowjobs, handjobs, etc.) which is normally a signal for me to ignore the game until it is more complete since the early stages tend to be light on content or only really provide the good stuff via dream sequences and the like, my personal pet peeve. I can happily say that is not the case here. While full sex scenes re not the majority of the content, those that are there are great and the foreplay-centric scenes are actually interesting and rather hot instead of the standard scenes that seem to be included just because that's what's expected/demanded. This is further enhanced by the fact that the relationships with most of the main characters have not even progressed to a sexual stage yet, leaving plenty of great content to come and yet somehow not feeling like we're lacking or missing out in the meantime.
I highly recommend playing this game when you have the chance and I cannot wait for more!