This is a review of the demo version; the game has potential but could benefit from a bit of touch up and adjusting.
The game makes the assumption that you're using a controller and there is no option to remap the controls via in-game settings. Keyboard controls work, but you'll have to guess what they are or go into the Unity settings menu on game startup to figure out what key is mapped to controller buttons. For a side-scrolling brawler the number of combat moves are lacking, giving you a ranged option that makes you stand still, a vertical drop kick and a sluggish three-hit combo. As far as I can tell you have no means of instant mobility (dashing/backstepping) and while you can sometimes knock enemies back, you cannot interrupt or stun them and starting out they hurt you far more than you hurt them. Thankfully, many enemies drop health items upon defeat that heal both characters, though you don't keep the currency you find unless you finish the level making starting out a bit of a slog unless you do prostitution for upgrades. Overall, while moving around isn't the worst it could definitely be a lot better.
The two character mechanic is somewhat unusual, with you controlling one shrine maiden and the other controlled by AI. The AI is not entirely incompetent but it mostly takes actions based on what you're doing; it tries to follow the character you control at a short distance, so if you choose to fight at range the AI will do so as well. Should you wade into melee, so likely will the AI based on it attempting to follow you. Of note is that the AI character completely ignores the slug enemies that both damage and turn you futa. If the AI character is turned futa, it will happily walk into your other character and instantly cause a game over, so be aware of that. When one character is grabbed by an enemy for mid-fight lewds, you can switch to your other character to free them; get both characters grabbed and it's game over and a restart of the level.
The game keeps track of what enemies have had their way with you and announces what general stage of fertility/pregnancy a particular shrine maiden is in. That said, it does feel like once an enemy has nutted in a shrine maiden multiple times she'll be giving birth to multiple children from that enemy in sequence. For example, let's say one has had sex five times, so she'll get pregnant from once instance of sperm, birth the child, eventually ovulate again and repeat the process four more times as there doesn't seem to be any sort of time decay on the semen it tracks and I didn't see a way to actually remove semen outside of repeated pregnancies and births. Another thing of note is that due to the side-on perspective and design of the shrine maidens, it can be difficult to tell exactly how far a pregnancy has progressed, occasionally leading to a surprise when one of the characters collapses and gives birth mid-fight (giving birth makes said character a one-hit KO when they get back up several seconds later, assuming they haven't been grabbed by an enemy since).
There are some minor performance issues that could be ironed out with some optimization, it does the not-uncommon thing of not properly using Unity's asset management system so it takes more than twice the disk space it needs to, and it can be a little hard to tell at first glance whether the guy running about is a civilian or your next rapist, but the game has potential.