Guide past the review below, highly recommended to read. If I had that guide before playing the game, I'd have given it a 5, that's how important I think it is.
The story is good and the corruption is very well paced. It's a bit of a slow burn, which is perfect. I appreciate how the NTR wasn't shoved in your face as much as some other titles. There aren't exactly a lot of CGs or animation, but I didn't feel their absence; the ones that exist were chosen carefully and used very efficiently. A testament to how well designed the game was.
The main issue is missing out on scenes and interactions combined with being a slow burn makes scene hunting and trying to see the whole game an absolute nightmare. The recollection room kind of sucks too. These problems knocked my score down to a 4. However, you CAN see pretty much all the scenes with only one playthough, so it's not an unfixable 4.
GUIDE:
Turn on auto-run, as usual.
Most of the stat gains and losses don't matter at all, and you only lock into an ending almost right before the end. You're almost entirely free to go max corruption so that you can see all the extra exploration scenes as well as the flavor changes in the Two Hearts screen.
It is possible to softlock due to lack of mana. To avoid, eat dinner at every opportunity and avoid using Luna's mana replenishment except for emergencies. Kurone's mana replenishment can help.
Paths:
- Flag + Confirmed
- Main Route (either No Flag, or Flag + Denied)
- Success (True End)
- Failure (Ending Variation 1 and 2)
The most compact way is to play through Flag + Confirmed, then revert to Flag + Denied to Failure. If you care about the nonNTR pure scene variations, revert to No Flag, in either case finish the game by playing to the True End (hold alt+enter to skip as fast as possible).
Keep a couple of save slots (it's very easy to accidentally save over a previous one or miss a dialogue option because it continued the story). This will get you Important Information key items, this will be used to be able to see all the corruption scenes while still being able to choose any ending.
Make sure to unlock all the information about the Treasure (for the True End). If you use every evening and night, you can also get all of Kurone's scenes.
Luna's small talk changes as she gets corrupted, be sure to check.
Paying attention to Two Hearts system updates, and using your brain a little to figure out where scenes might be, it's very hard to miss anything. Use the "Look Inside the Mansion" map to help.