"Horse legs?" Jake said aloud as he looked over the options. "Well, that seems different, hooves would be different." He selected the option, and hovered over the button to begin.
"Right.. pants." He shook his head, no sense wasting a perfectly good pair of jeans by bursting them open with horse legs. So he stood up and kicked off his shoes, then quickly stripped his socks and pants, tossing them onto his bed. Left only in his briefs, he sat back down and clicked the button to begin.
A strange sensation began immediately in his feet. His middle toe on each foot was suddenly growing in size as the rest of the toes shrunk away. The nail was becoming hard and black, thickening until it capped the one single toe completely. His whole foot was quickly rearranging into an unguligrade shape, the core of his foot lengthening as his heel pulled up off the ground. He set his new pair of hooves on the floor. It felt weird not to feel through them, but they felt sturdy enough.
His calves began to shorten, even as they thickened with new muscle, short chestnut colored fur started growing up his legs starting at the top of his hooves, slowly following after his legs altered in shape. Cream-colored feathering sprouted out around his hooves in a shaggy fetlock.
The fur proceeded up and over his knees as his thighs began to swell with muscle, tendons and sinew twisting about to support his new posture. Then he noticed something strange. The front of his underwear was starting to bulge, and more than the hard on this change was giving him could account for. He pushed his underwear down, exposing his crotch, and a cock at least three inches longer than he remembered it being flopped free.
It was thicker, too, probably twice around what it was before the change, and it didn't seem to be stopping. As chestnut fur creeped up his thighs, his cock continued to swell in size. His balls were inflating at a breakneck pace, first growing to the size of eggs, then oranges, until he had a pair of grapefruit hanging down between his legs. He actually had to shift and spread his legs as he sat to make room for the over-sized orbs.
Fur started growing over his distended scrotum even as he was now sporting a cock at least a foot long and rock hard. Parts of it were darkening, the flesh becoming a mottled mix of black and pink. One hand was no longer enough to support the monster, nor could he wrap a hand around it, it took both hands to hold it up, and almost against his will he began to stroke his prodigious member.
The head of his cock lost it's mushroom shape, pushing upwards into equine flare, a ring forming around his cock about halfway up. Jake leaned back in his chair, running both hands up and down the shaft, it was now as thick around as a soda can and an obscene sixteen inches, where it seemed to be stopping. Skin started bunching up around the base of his shaft, pulling it up against his stomach to right below his navel, a large sheath to hold his large cock.
With a moan, he shot his first equine load, massive balls churning as he shot stream after stream of hot sticky cum. Some of it hit the ceiling, some landed on him, and more landed on the floor.
He sat for quite a while in post orgasmic bliss, long enough for his cock to soften and slide back inside his sheath, just the top of his flared head showing at the end, the whole thing hanging pendulously from his crotch and lower stomach. Grabbing a towel, he began trying to clean up the mess he made. It was definitely odd standing on his hooves, and his balance felt a bit off. He didn't have a tail, either, in fact, the fur didn't even quite cover his ass.
He looked at the computer screen with the program waiting for more instructions and wondered..