I finally return from my trip. First of all, I must thank you for your fair criticism and I'm sorry if my last reply was short; I replied your comment from my cell phone during my travel and to be transparent, I'm more comfortable writing on my computer.
Like I said on my previous post, I wanted the giantess growth event happened a long time ago but didn't thought about the immortality aspect and It wasn’t my intention to make the characters almost immortal. I plan to do some rework of the characters back stories for 0.1 release and I will add some details regarding their longevity and how they could die because they don't live forever.
Speaking of longevity, it depend the perspective. 500 years from a human point of view is indeed a long time, but for a giantess with a very long life span, it's just a norm. After all theses years, the giantess continue to evolve but more slowly because there is less people in this world to share knowledge with so technology didn't progress that much. Patty (aka the pink-haired girl) is the smartest one around, she do a lot of tinkering and create some devices in attempt to overcome some challenge the giantess face currently, but most of her invention failed. If you've checked Ophelia's introduction, she told the MC that Patty already attempted to create a shrinking device, but didn't work at all. She will get it working later in the story but the shrinking capabilities will be limited. For example, her device can shrink down a giantess at 10% of their size, meaning for a giantess of 120 feet tall, she will reduce to 12 feet maximum and last for only for a few hours before growing back. Patty will explain the technical reason for this limitation, but I won't spoil it right now.
As for the reproduction topic, this is an upcoming challenge the giantess will face with no male around, but due to her longevity, it's not a big deal at the moment. The giantess still have desire for sex, they do masturbate time to time to get some relief, but they quickly get horny and have a hard time to keep control of themselves with the MC is around and have a strong desire to mate with him. The MC will be the key to solve the reproduction problem in that giantess world but the idea here is to open a harem story path later in the game. but you can do a love story with one of the girl as you want. The MC can still return to his own world, but there will be a story twist.
I'm not sure about your statement on "not all guys have a giantess fetish", but this is a giantess fetish focus game, that include minigts up to gigagts, and some MC shrinking scene and will remain that way for the whole game.