This game is, basically, Horrible Stalker Nephew Simulator 2017. I had higher hopes given the developer's pedigree with Lust Epidemic (which was essentially Harem Corruption Simulator 2019), but this game essentially features a completely irredeemable main character who literally does nothing other than lie, cheat, and more or less rape his aunt in the space of less than an hour of gameplay (I was 100% complete within 45 minutes without even using the walkthrough). LE had a MC with some depth, including a white knight syndrome with a desire to protect the women from a nasty circumstance in spite of his corruptive and libere sexual attitude (although, avoiding spoilers, absolutely no one learned anything in the end). In Visiting Aunt Sara, by comparison, every sex scene except for the last one is "semi-consensual", i.e., coerced sex where the aunt eventually grants consent either in flagrante delicto or a mere moment before beginning copulation even in the midst of her protestations, overcome only by alcohol, sexual desperation, and psychological manipulation.
Nothing he does is intended for her benefit; his goal, his only goal, is to get his aunt drunk and then rape her silly. I don't tend to kink shame, but non-consensual/questionable-consensual is literally the textbook definition of obscenity in most countries, so it's no surprise he got shitcanned from Patreon for this stuff. I wouldn't be quite so radically opposed to it if it was at least identified as such, but the game was described more as a seduction game; it wasn't "taboo" so much as "a record of a (virtual) crime in progress". Quite literally all of the MC's interactions, even with a completely sexually available and willing woman, would have landed him either on the curb or in police custody had he tried them with any other real person.
My personal rating would be 1/5 or 2/5, but acknowledging the quality of the work that was done and the moderately good quality of the (~15 frame) animations, not to mention the fact that the aunt actually looks her age compared to other products, I can give it a comfortable average. Not great, not terrible, especially due to its miserably short playtime. (It's games like this that make me thankful for F95, because I want my $0 back.)