May Space Project be damned to eternal torture for making this game (Their fourth, supposedly.) It's well animated, featuring tons of girls... all of which, excepting one, have penises. This game contains enough dickgirl porn to satisfy... well, whomever gets off on that kind of thing.
The (now defunct) ADVGAMER blog had a pretty thorough review (in Japanese) of this game, which mentioned it only really loosely related any scene to another. If you're not using the mouse, control is via the keyboard, and the Z and X keys.