A fun (though not sexy) game with great mechanics, good writing, decent animations that serve the story, and mediocre porn that doesn't integrate with the gameplay in any meaningful way. If you're looking for a deck-battler that adds a couple new, interesting mechanical twists, give it a try. If you're looking for something to fap to, look elsewhere.
The best part of this game is the twist it brings to a standard card-battler. It has a few standard mechanics: You have a deck of cards; cards cost energy to play; you are trying to reduce enemy hp to zero and keep your hp from reaching zero; you can modify which cards are in your deck and the cards themselves to change what your deck does. The main difference is that instead of drawing a limited number of cards per turn, you simply start out with access to all (7-10) cards in your deck, but each can only be played once per fight. When you run out of cards to play, you have to sacrifice one to get the others back and continue fighting.
Some of the cards grant a passive effect when sacrificed, and this buff continues to benefit you until the end of the dungeon. Sacrifice a Fireball and all your attacks will add Burn. Sacrifice "Bloodletter" and you'll heal every time you hit the enemy. The trouble is, every time you sacrifice a card in this way, you can't play it again even in future fights until you find a rest point. You may choose to sacrifice cards early just to get access to the buffs, then find your deck quickly dwindling faster and faster as you desperately hope to navigate to a campfire. Sacrifice too much, too soon and you'll leave yourself too few cards to finish fights. Do it at the right time and you'll find yourself confidently standing before the dungeon's final boss, burying them in damage-over-time and automatically buffing yourself as you stack massive damage.
The game also respects players' time. There are a couple side-dungeons that take much less time to get through and are designed to quickly give the player resources, preventing excessive grinding from ever being necessary. Everything's streamlined to make it easy to modify the cards/deck and get back into the action.
The story is your standard fantasy "heroine likes Isekai'd MC just because he's there". It is well written enough to give the heroine enough personality to carry through the scenes. If you can turn off the part of you brain that asks, "why the hell would that girl like this guy when he isn't really doing anything and doesn't seem to have anything to offer?", you may even find it romantic.
One big drawback in the story: It teases mysteries that remain unresolved, even by the end. Since the h-scenes aren't very good, gameplay and story have to excel, and it was frustrating to reach the end and find there weren't answers for some of the game's questions.
The sex content is vanilla and decently animated, but feels like an afterthought rather than a natural progression of the scenes and characters. The sex content was designed to be removable - there's a setting marked "Good Kids Mode" that eliminates it from the game entirely. Even moreso than many games, the scenes feel tacked-on, occurring at the end of boss fights or during random moments with nothing about the moment-to-moment gameplay feeling sexy. When the last scene of the game was interrupted with an h-scene, it didn't feel erotic and rewarding, it felt jarring and inappropriate.
The mechanics of this game stand-out, and I wouldn't be surprised to see some form of them pop up in a non-erotic game release. Fans of card-battlers and deck builders will find a lot to like here. If you're looking for great sex scenes or arousing gameplay, keep looking.