Thought I give this a shot as it had a 30% off launch sale, but it isnt worth its triple A price tag.

Koi-Koi is essentially a 3D Visual Novel, only dialogue, a few choices that dont seem to matter so far, and you can move the camera around in areas, thats what you get. The whole game plays in one single location, and it looks graphically like they imported it from a PSP/3DS game.
The adult content is very scarce and the censorship is awful. Instead of having the usual pixelation like most eroge do, this has just a huge heart texture plastered over the private parts.

You can buy Gal*Gun 2 for half the price, the Visual Novel sections play exactly the same as Koi-Koi, but Gal*Gun 2 looks better, offers a lot more ladies and routes, and it even comes with gameplay sections. So yeah, hard pass on this, you can get similar and better games for half the price.

Tough recommendation for this game as other visual novels at its price point are just overall better. Even at its sales price (50% off), I only consider it cause there is a develop's patch that has an explicit mode. However, there is no auto or skip read dialogue button as you have "hold" down your middle mouse button. Graphics are fairly dated and there is little to no modding that I've found. CM and KKS blow this out of the water especially with their massive modding community.