Let me get one thing out of the way first, before someone claims that this review score gave them false expectations. In terms of variety of sexual content, so far at least (Chapters 1-5), this game is actually kinda poor. It's mostly handjobs and blowjobs from two girls, with occasional anal sex with one of them. If you're only here for the lewd scenes and you're especially hoping to see some vaginal sex, like I was, this game might disappoint you. Consider yourself warned.
So why did I give it 5 stars anyway? Well, aside from the fact that there's a clear promise for more varied sexual content in future chapters, including vaginal sex... I did so because if you overlook its current shortcomings in terms of lewd content and actually give its story a chance, I believe you will be thoroughly entertained. The plot is silly and the characters are ridiculous, and I meant both of those things I just said in the best way possible. What really pushed me over the edge and made me give this game 5 stars instead of 4, is the writing. This game features some of the most ludicrous dialogues and internal monologues I've ever read, and again I mean that in a good way. I don't usually laugh out loud at things VN characters say, but I did several times with this one.
Speaking of characters (slight spoilers ahead, but nothing too secret), MC is literally a coomer, his sister is a hardass on the outside but a sexual deviant on the inside, and his mother tries to be the pillar of morality her children need, but deep down she's just a horny, sexually deprived woman who's thirsty for her son's cock. A few more girls have been introduced but haven't had a lot of development or screen-time so far. However we can already safely tell that MC is working on creating a harem in a post-apocalyptic zombie hellscape, starting of course with his own blood.
Speaking of post-apocalyptic zombie hellscape, if I'm being honest it merely serves as the backdrop for this story; While the protagonists do have to deal with zombies every now and then, and will have to scavenge for supplies, the story is much more focused on how (and with whom) MC will get to drain his balls. It's a porn VN, after all.
In conclusion, K:TR is a pretty unique, well-written porn comedy that might be a bit slow in the development its sexual content but seems to be on the right track anyway. I cannot guarantee it will be your cup of tea but it's damn well worth a try.