Bright Lord has a lot of potential. If you read nothing past this line, take the review as a "Definitely worth a try" recommendation!
The overall render quality is in the upper end of what you tend to see in this style of game and even though there are some technical issues with them, they work well enough to not prevent immersion, if you can get onboard with the body and (especially) the facial proportions.
The Lighting is functional most of times, though I can't yet give a final verdict on that since at the time of playing my monitor had fucked up brightness and contrast thanks to our eternal friend: Windows. I'll revise this part of the review with the next update.
The most important part about the renders is that expression, lighting, scene construction and so on significantly improve during the game progression to the point of where, after the earliest scenes, they fit the narrative much better.
The animations need a lot of work. For now though, I am confident that the issues can be worked out since only one of the animations is really bad and all the games aspects are clearly still in very early stages.
The relationship plot isn't anything new, but that's neither here nor there. Certainly the Mystery plot beneath it promises more than enough originality for your successful incest -AVN.
The characters are, while more or less presented in trope typical fashion, similarly well characterized by the dialogue and good starting points for real differentiation and character work. There is a reason why the "older sister --> bitchy sexy girl; mother --> sexually frustrated and feeling lost in life; younger sister--> insecure and innoccent " dynamic is so popular. Not straying from it is perfectly fine. (and honestly, there are only so many ways you can switch this up anyway)
From a technical aspect, the writing is also decent enough, with some but mostly non-intrusive errors and stylistical blunders here and there that shouldn't stop anyone but the most demanding players from enjoying the game for what it is. Especially with all the engrish games out there.
All in all, the overall unweighted rating would probably end up being 3.5 Stars, but I'm upgrading that to 4 Stars simply because not only does everything about the game come together well but there is also a lot of improvment noticeable during the progression up to where the game stands right now. I am even tempted to go with 4.5 stars and I will definitely revise the score after the next if not the next two upgrades if the current trajectory holds true but for now I feel it is too early to give out that rating, simply because we are so early in development.