having multiple characters interacting or penetrating the character that is in the restraint/chair. 

Not sure how feasable this is but id love it if it were to be in the game. 

Allow players to multitask with different actions. Some possible examples include:

Breast fondling while performing vaginal or anal penetration.

Breast sucking while providing masturbation

Blowjob while face-sitting (69 position)

Have Subjects react to Orgasm Denial and include toys such as Chastity Belts.

The foreskin of a humanoid penis can be customized, like the how long/short the foreskin is, or set it to phimosis so the foreskin would not retract even after erection.

I think a clever way to add a little more depth to the gameplay aspect of the game might be to implement a series of different debuffs, restraints or limitations to some NPC's that have to be overcome.

Some of these could be simple resistance to certain types of transformations that require you to research a way to overcome it. Some could be a propensity for a certain type of event to happen no matter what you're doing to the subject, or perhaps a small chance of a completely random effect occurring. Maybe even negative traits that simply lower output if you use the wrong types of experiments on them.

However, I think it would be rather interesting to determine these effects independently of how a subject generates their wants/desires and requests of you. Perhaps even allowing for massive bonuses if you help some poor soul with, say, a shrinking fetish that has traits that prevent you from doing it.

This would be incredibly useful from a gameplay perspective. The ability for me to write in a notepad, "Particularly good subject for farming Avium" or "Responds best to my _____ character" or something like that... WITHOUT me having to open Notepad on my actual computer would be extremely useful for when I'm trying to get certain resources or invoke certain responses.

It would probably be really simple to program in.

Not to mention, there's probably plenty of people who would love it from a roleplay perspective. Some people would probably get really into writing up an entire lab report. If this notepad thing proved to be popular, it could later be considered for adaptation into Racknet. People leaving notes to the character's creator about experiences they had with their characters. Stuff like that.

But I'm getting ahead of myself. A simple box of text connected to fav'd characters would be an overall useful tool for the practical researcher.

The ability to input an exported customized character as a test subject in the game.

i think adding the ability to fill someone with so much cum depending your species that they start to bloat from the ammount of cum, or be filld by water and or air would a not only a bit more realism to the game but also appeal to people who are into cumflation and to those into inflation

I noticed that R2CK's Trello has a card about preventing tailhole intetactions unless subject lifts their tail on their own. Would it be possible to force their tail up manually and hold it in place by hand or strap it to the rack and the like instead?

Vaginal or anal, getting subject to suck on fingers after they've been inside them. Would be wet for vaginal, maybe could transfer cum too.