Female Body Builder or Amazon?
Tossing a couple of theoretical daydreams for a games I'd find some fun in.
Some ideas are more than likely repeated from other threads and swapped from games involving cars, mecha and pocket pitbulls.
(EDIT- Reason you linked to exactly the thread I dimly remembered thank you for potent recall. :> )
There could be a Female Body Builder manager/trainer simulation with different modes based on the difficulty. Easy mode might have the sliders for genetic potential wide open and allow one to craft a one in a million covergirl mesomorph for whom unnatural gains are perfectly normal.
Normal mode might have the specific numbers hidden and instead have victory come from prudent nutrition and setting the right sorts of schedule. Specific body types for potential trainees could still be chosen but the overall best muscle groups would have to be discovered over months of game-time training. Minigames could be resisting straying from diet and coming in as 'cut' as humanly possible.
Hard mode completely in the dark as to the trainee's entirely randomized potential. This would be the most simulation heavy but also be unrealistic for the purposes of increasing difficulty. Taking into account that the conditions for training might not be entirely optimum. Importing a trainee from Hard mode into Normal mode might add a bonus to the willpower stat just for being able to do so much with so little. Hard mode might reflect those FBB'ers that have to train in secret due to their society's ill view of buff ladies. The importing to lighter difficulty could be handled by the trainee making it to a better situation.
Numbers that could really give the players a sense of accomplishment, as well as the virtual FBB, might be 'Gains' reflected in some equation resulting from the interaction of 'Calorie Intake', 'Lean muscle Mass' and 'Weight Class'. Gains could also be modified through the most popular feature 'Measurements'.
The math aspect seems the most possible with a rough polygon model that changes based on the factors involved in training and success in each minigame.
Appearance would be entirely customizable in Easy mode with Hard mode being entirely randomized. Normal mode might have Randomization shouldn't take forever in order to allow players to get some crazy weird combinations in their trainee's potential.
This engine might also have a Strength Contest mode if a one wants their trainee to put those muscles to greater use than occasional pageantry.
Grip, Agility and Endurance would factor into the final Strength ranking.
For a weird angle money values might be connected to training duration, dieting and suppliments. While it shouldn't impact gameplay an easily observable stat indicating just how MUCH money and time, both duration of play and in-game,it can take a trainee to make it to champion would serve as a gentle reminder that people go down this tough path in reality.
So the math of the simulation might be a good first step. Once the matrix is done any sort of connection to the graphics could be multi-tasked by other enthusiasts shortening your work load considerably.
If polygons are too much of a pain in the arse might the Fire Pro Wrestling school of nappy sprite art be preferable? Heck there have been some amazing Flash games that simulate changes to figure quite convincingly. You're the journeyman game forger you tell us.
Mirages of a muscle trainer sim with the drop-in graphics customizability of MUGEN Fighting dance behind the eyelids.
