The Alpha Underground is a sci-fi erotic visual novel about a shady underground facility that experiments with muscle-growing their helpless test subjects.

Francis is a grumpy old bear who gets a chance at settling up on his massive debts when he is referred to The Alpha Underground. All he has to do is sign away his rights and become a guinea pig for some weird experiments held by a perverted yet genius scientist. Francis gets paid per pound of muscle he gains while undergoing this trial so if he wants to make a ton of cash, he'll have to put on a ton of muscle.

How will Francis fare surrounded by other test subjects, mysteriously masked and jacked servants, and all the weights he can lift?

[From Itch.io]