If you pull your Cock completely out of her/his Mouth/Pussy/Ass, you can cum on her/his Face, her/his Ass or on her Pussy.

Knot max/min diameter
Tongue width / shape customization. Tongue play?
Tail base diameter, taper ratio, tail tip taper ratio
Ear height/width/taper - Better floppiness
Snout length/width/taper
Better/different teeth - or a custom teeth inlay system

It's the little things :)

Making a gay or straight test subject have sex with the gender they do not like. could be done with portals, or just machines, or persons.

I'd like to see the ability to go sword to sword with a subject and use a single fleshlight/masturbator sleeve on both. Trying to time both the player and subject cumming in the same fleshlight at the same time could be a fun objective.

This is similar to http://fek.userecho.com/topics/242-internal-or-x-ray-viewer/, but I have a feeling it may be easier to do than having all organs in 3D:

On inserting an object into any orifice allow a 2D cross section view to be displayed of the object moving inside. This would be especially interesting for delicate procedures like sounding, urethra play, vaginoscopy / uroscopy. It would combine great with http://fek.userecho.com/topics/401-/

Hey Fek, Is it possible that you could make the largest penis size longer in the character creator? like 30cm /12 inches without madscience? Because its like the longest you can make them is 5/6 inches :( I know chemicals to make your dick bigger is coming but, I mean in the character creator? Will there also be other kinds of penises too? Love the game so far!

Instead of having the size of a character's knot entirely decided by their overall penis size, a way to change its size individually would be great if players want something like a bigger one on a small penis, or a more modest one on a bigger penis.

have more than one way of bondage like straitjackets,rope,latex,mummification ways,blindfolds and ball gags with or without the rack

All right here me out on this one. This would be a very late game item that would allow you to put subjects in to "travel time" (whether its just a mind perspective thing or the real deal is up to fek). For example if you want to have an extreme edging session you put the subject in the machine set how many minutes, hours, days, or even weeks you want them to "experience." 5-8 minutes later you come back to the machine and find a subject that would be very exhausted from edging.

I think this would allow some fun interactions with the dialogue system and to even use it as a punishment tool

Don't know if its technically possible, but allow the pleasure self button to be used everywhere in the lab, not just while on the rack.