Open game, right click. You'll see these options in the top right corner.
The top one is the character customization screen. It's pretty easy to figure out. Skin tone, face shape, ear shape, etc. The bottom is where you actually get to use the clothes you have earned:
http://www.ulmf.org/bbs/picture.php?albumid=183&pictureid=2124
If you click on the red text you'll be able to change clothes.
The next option gets you into the game itself. It starts off from wherever you left, no need to worry about loading or saving.
The third option down goes into recollection mode, looking like this:
The top option next to each picture, with the percentages, is recollection. The second option teleports your character to that location. This makes moving around the map much faster obviously.
The fourth option exits the game, and the fifth option just showcases the 3d images.
Now for the actual game...
The controls on the right side are as follows:
The Sexy3d thing is just sort of a picture-in-picture mode. I don't know if you can control it other than changing from off to front to back to off. The three options in the top right corner I'm also not sure on; the first one takes you back to the menu screen, and the third one goes to the cg recollection mode, but the second one always seems to be greyed out for me. The next group of options (where one is highlighted red, there are five of them) seem to control your speed; I haven't found any use for them aside from the middle one (third one down) which makes your runspeed significantly faster. The rest of the options are just camera control.
The controls on the left side are as follows:
The red arrows are just movement. I find it easier to use WASD personally. FPS is self explanatory, not sure what anime= means. Seems to have something to do with runspeed. The thing in red is a progress meter of some sort. You get +X number whenever you unlock a new sex scene (or gain new clothes I think). The more invasive the sex, the higher the number. I think you have to have this at certain amounts to unlock certain options.
The top left corner is what you really want to pay attention to. That option you see in the screenshot is always there as far as I can tell, changing your movement from run to walk and vice versa. However once you're in an area where you can interact with something, more options will appear. For example, if I turn around and look towards the tentacle monster....
The new option appears. Once you click that, you'll go into the sex scene, where more options will appear. White is stuff you haven't done yet, yellow is change positions, red is stuff you've done already. These options will also appear whenever you're near a button you can press or an item you can pick up (such as clothing).
As far as I can tell I'm only missing a few things, and this particular monster in the screenshots is one of them, all I get when I try to interact with it is this text box:
Which I can't put through AGTH for some reason. There are also two boxes on the top floor that I can't open (I managed to open one but still get text yelling at me when I try to interact with the remaining two). Not sure what I'm missing.