Tsuisou no Augment, when I first played it, blew me away. Part of it was because it was so surprising, part of it because it was just that good. Thankfully, it turned out to be just as good on a second playthrough.
First, this VN doesn't fall into any of the standard genres. Most of the game is hilarious, some of it is romantic, some of it is hot and sexual (seriously so), there is serious drama, and there is even some guro, though of limited scale. The game begins with Hideya, the protagonist, lying in an old folks home at the age of 80, unmarried and looking back on his life, seeing it as empty and meaningless. So, quite naturally, he takes up a nearby fruit knife and stabs himself in the throat, twisting so that the wound opens nicely, spraying his blood over his room. To his surprise, this isn't the end... he wakes up in a park, sixty-something years before, in his young body, with a hideous creature calling itself a shinigami floating in front of him. The shinigami explains to him that it, Augment, wants to take his soul at the peak of happiness, so having him die of suicide after an empty lifetime was inconvenient. As a result, Augment took him back in time at the moment of death so that he could find his happiness - mainly a romantic life partner - so that Augment can use his soul after death to purify his own.
So begins Hideya's dramatic journey to gain happiness... or not. Hideya's personality isn't exactly Japanese-standard, so things don't really go the way you would expect with the standard VN protagonist. Hideya is a fast-talking young man who takes an unholy pleasure in derailing conversations onto random topics (which are disproportionately related to sexual fetishes), which makes most of this game hilarious to read, since Hideya absolutely cannot stop himself from derailing even the most serious of conversations. A lot of the choices in the game are worth exploring alternatives to, if only for the few hilarious extra lines they grant you, lol.
The three heroines of the original game are Shiho, Satsuki, and Nami. Shiho is the protagonist's osananajimi, who began to distance herself from him sometime in middle school. She is a kind-hearted and generous young woman who studies obsessively. Satsuki is a girl from the next class over that Hideya meets on the street one day while she is stomping on her older brother's head. She is the game's tsundere, often saying the opposite of what she means, and she is a brocon that happens to beat up on her brother regularly because he is rather... annoying. Nami is the younger sister of the protagonist's class teacher. She seems quiet and mysterious on the surface, but she is actually rather expressive... though that expressiveness tends to come out in reaction to jokes, opportunities to put down her sister, and opportunities to blackmail her sister (the teacher is a total siscon).
In Shiho's path, you confront the reason why she put a distance between herself and Hideya, and the reason is fairly... traumatic. It is a reason that is all-too-common but no less tragic for all that. In this path, there are too endings. One, the one that is available from the beginning and is the 'true' ending for Shiho, has Hideya borrow Augment's power in order to right the past wrong that so twisted Shiho's life. The other has the protagonist accept the current Shiho for who she is, loving her including her scars. Depending on the individual, it is questionable which one is more touching, though.
In Satsuki's path, you find yourself confronting yet another issue common to pretty and friendly girls everywhere... in this case, the endings are slightly less distinctive, because the end result differs so little, though there is a third, bad ending you can get if you pick the path to the true ending and make the wrong choice at the last.
Nami's path is a little different, and her true path is pretty guro (if you look too close at the CGs, the average person will probably need a barf bag). Nami is the cutest of the girls when in love with the protagonist, but that just makes the guro parts worse, lol. Her non-true path involves evading the guro events to reach a normal happy ending, and in that sense, hers has the most disparity between the endings.
The Tsuisou no Aumgent FD (also pronounced Tsuisou no Augment) covers after stories (between the epilogue and the ending of the stories in the first one) for each of the three original heroines, as well as adding on paths for Augment, the protagonist's older sister Youko, and Nami's older sister. The after-stories are basically a treat for readers who wanted a little extra ichaicha material from the heroine paths and more Hideya doing his level best to prevent conversations from going anywhere. The Youko and Minami paths are both about two-thirds the length of the original heroine paths from the original game, and while they are good, I honestly preferred the original heroine paths. Augment's path is basically a joke h-scene.
Overall, Tsuisou no Augment is one of the more memorable games I've played over the years... and one of the few games where I spent most of the game laughing my ass off but could still cry at the important parts. This is no charage - the paths are a bit too harsh on the characters for that - so this won't attract those interested in that sort of game. However, it does have nice romance with serious drama attached.