with the upcoming update adding fertilization and pregnancy I'm absolutely hyped, but I have a few optional (toggable if added) add-ons to that mechanic and a few other different suggestions
1st) making it a bit of a more hard-core and challenging experience a deterrent could be added if impregnated, within the first trimester a chance within a few days you'll get morning sickness and a debuff labeled nausea, you have less health and are best to rest for that day. A second part would be as the characters pregnancy progresses there's a chance they may stumble a bit having to adjust for that weight making it harder to escape enemies.
2nd) adding a "parental instinct" to the character, when in the second to third trimester the character may get a buff for strength and endurance to protect their young, the buff activating when two or more enemies are on screen to try and evade unwanted situations, it could act as a incentive to become pregnant too giving the character a stronger swing at the cost of energy
3rd) the chance the character can encounter the "father" of the characters young. If let's say a 10% chance the wolf showed up in the forest it would be the father unless slain after insemination, if the father of the young sees the character it will be passive and do a friendly animation, the wolf could do a sniff of the air and could move slowly and low towards the player till it got close enough to be by their side, maybe a lewd animation of sniffing the characters crotch and with the goat man a touch of the belly, once the player and "father" are together in that level the father will fight other enemies even their own kind till the player leaves the level and back home.
4th) elements of birthing, it's not everyone's cup of tea but it's my odd ball specialty. With birthing elements there's 4 stages,
Stage 1 is contractions and slowed movemnts, if a pregnancy is 3% from being done they will start and intensify untill stage 3. With contractions the character will hunch over a bit and grab their belly or if late enough in the stage their crotch, when a contraction happens they will make the injured sound so audibly signal that they better start making it back home, once contractions start (with a standard of 7 days for a pregnancy cycle to complete) they have 1 hour to get home, once that hour is up we move onto stage 2
Stage 2, stage two is even further slowed movements followed by a water break, it will wet their crotch and when their water breaks the character will panic if still outdoors and not at home, they will stagger for 45 minutes then stage three will happen.
Stage 3, stage three is the most intensive out of all of the stages, it's the labor stage, when labor hits the player it will slow them down till they have no other option then to lay down, that lasting for 15 minutes before having to lay down. The player once in this stage having to lay down can op for standing up and trying to move with button mashing ie the X and A key to move left. If the player has enough strength they can power through and possibly make it home. But If the player is a first time mother or too weak they will collapse to their knees then it's stage 4
Stage 4) Delivery, once the player is on the ground either by surrendering controlls when they first go down or by running out of strength they will have to enter the delivery stage. This stage would consist of having to give birth to your young, depending on what impregnated the player it will either be a challenging delivery or quick, example would be the wolf being a quick and easy birth but the goatman would render the player pushing for a while, birthing would be done by mashing two or three buttons in sync the better in sync the quicker the birth, and with the birth comes exhaustion each push takes a percentage of your stanima, thr player can take brakes to regain stanima but it will make the prossess longer. If the player runs out of stamina they will pass out and wake up later with no more pregnancy, if the player successfully births their young without passing out they can take them home as a companion, if the player is at home when they give birth they will allways keep their young even if they pass out. Wolf can be a pet and the goat man can be a background still that appears in different rooms doing background tasks like washing dishes or laundry maybe I'm the back yard taking care of the pet wolf. Once one is obtained (wolf or goatman) you won't get another by doing the prosses over gain.
This can also be applied to oviposition aka eggs, tentical can lay eggs in the player then they have to push them out in order to be back to maximum strength and speed.
As for non fertilization suggestions,
Ease of modding? Make the game easy to add user made content, with user content it could actually boost the games life and popularity.
Second would be stronger and different enemies maybe a bandit that can drop down from ceilings and take advantage of the player and being stronger then the player. And a new kind of plant type that will lure the player in with gifts such as food or clothing a few times then when the player has its "trust" the plant can impregnate them with a solid egg or maybe cure their heat. If it's a male player maybe drain them of their semen
Lastly would be weapons and clothing, a crude gun could be made or found using a lot of expensive hard to find materials ammunition has to be made from them too only should be used in a dire situation it's a two to one shot weapon. Next is clothing. I think that clothing should get a minor rework, if your character is in a heat they can have their pants and underwear get soaked making it easier for enemies to take advantage of you or if you put pants back on after being ejaculated in it can dirty them. Skirts should act as a covering but still allow for lewd events with it on by going under the character if they dont have underwear on