"Alright, just to make sure it still follows the same functionality, I'm going to start by changing the colour of your fur."
Mike nodded the affirmative, and Jeff clicked through the options.
"Brown!" He became a chestnut brown rat, only to return to white moments later.
"White, black!" He was suddenly as black as charcoal. "Black and white!" His fur settled in a nice pattern, black on his back, with a white underbelly underneath.
"Right, so I think that works well enough. Now. I wanted to give you something else. I'll see if you can guess what it is." Jeff winked, typed in something, and then pressed enter.
Mike felt a little tingle in his tail and squeaked, trying to turn around to see what had happened. But, it didn't seem to have changed, maybe it had grown a centimetre longer at most, but nothing very noticeable. He turned back to look at Jeff, who laughed.
"Try curling it." Mike did, and suddenly found he had immense control over the muscles in his long tail. He coiled it around like a snake, before unwinding it and waving it in the air. "I made it prehensile! Basically, you get another limb so you can grab and hold onto things, which might come in handy. It's also a bit stronger than it should be, so you should have no trouble lifting your own little body weight with it. Her, try it out."
Jeff held out a pencil, and Mike quickly wound his tail around it. As it was lifted from the table, Mike found he could hang perfectly suspended in midair with no sort of stress on his tail muscles. Bending them, he found that he could even do sit-ups with it! He squeaked happily as Jeff put him down.
"I know, right? But that was just the practice round. This machine can do a lot more." He cracked his knuckles. "Ready to go again, Lab Rat?"