A/N: To the guy who keeps asking about Knuckles, Cream and Amy: They'll be in the series at some point or another. Just have patience, OK?

Like Labyrinth Zone, Mystic Cave Zone was fairly well-lit inside, by means of lanterns strung up alongside the tracks on the ground, which meant that this grotto was probably man-made. Judging by the vines growing from the ceiling in addition to the rust and rot coating everything, the Zone was in disuse.

"Do you suppose this was once used as a mine?" asked Tails.

"Could be," replied Sonic. "Keep an eye out in case Robuttnik's usin' any equipment for himself."

"Right."

Sonic and Tails kept running, encountering more SWATbots and Caterkillers in addition to those burrowing robots that Sonic had encountered at the aforementioned Labyrinth Zone. As with the ones that had come before, they were also a piece of cake to defeat, but Tails nearly got pierced by one of the burrowing robots' drill noses. Nevertheless, their stride remained unbroken, and when the tracks came to an end, they jumped over the barrier and landed on a wooden platform that was built over a nearby pit. Unfortunately, the supports were old and rotted, which caused it to give out when Sonic and Tails put their weight on it. Fortunately, they jumped to the next ledge just in time. However, Sonic's Hedgehog Sense told him to stop, so him and Tails came to a halt before a massive pillar of stone came down and crushed them.

"What was that!?" said Tails.

"Whatever it is, it's probably one of Robuttnik's traps!" said Sonic.

When the pillar had retracted sufficiently, Sonic and Tails charged past it before it could flatten them. A few ways down, Sonic and Tails encountered another robot they hadn't seen before, which resembled a firefly. Sonic jumped to hit it, but less than a second before he made impact, the firefly bot emitted a bright light, which gave the Blue Blur a nasty shock when he touched it

"SONIC!"

After Sonic plummeted to the ground face-first, Tails rushed to his side and jostled him in an attempt to get him to stir.

"Sonic, wake up!"

Sonic groaned and pushed himself to his feet while shaking his head.

"Are you OK?" asked Tails.

"I'm all right." Sonic dusted himself off. "That was a hell of a shock, though. Remind me never to touch those things again while they're lit up like that, ya dig?"

"I will. Can you still run?"

Sonic stretched his legs. "I don't see why not…"

Sure enough, Sonic was still able to run, and Tails followed him deeper into Mystic Cave. Just as the two were about to land on another platform, Sonic's Hedgehog Sense tingled again, and this time, it was because of another new robot that jumped out at them. This one resembled a Caterkiller, but with a blue body and yellow underbelly, plus two black mandibles on the front. Having evaded it the first time, Sonic and Tails waited for it to retract, jumped up and smashed it the next time it attempted to lunge at them. With this machine dead, they proceeded further into the cave, occasionally passing by abandoned mining equipment such as pickaxes, mine carts and empty wooden crates. Eventually, they came to a dead end, with nothing but a short gap and what appeared to be a bunch of logs blocking them from going any further.

"What are we gonna do now?" asked Tails.

"Let's jump down there." Sonic pointed to the pit.

"But it looks really dark! We don't know what's down there!"

Sonic looked down into the pit, and sure enough, it wasn't illuminated well enough for them to see to the bottom.

"On second thought, you're right." Then, Sonic grabbed a nearby pickaxe and started poking at the ground with the head. "There's gotta be a secret door or passageway or somethin' around here…"

While Sonic was poking around for another means of ingress on the ground, Tails was looking at the vines on the ceiling.

"You know, Sonic, I find that when I believe in myself and fly high…"

Tails flew up to the ceiling and grabbed a vine-covered switch, which when pulled down resulted in the logs being lowered to reveal a bridge. He then jumped down.

"…the solution presents itself!"

Sonic dropped the pickaxe and gave a thumbs up. "Great thinkin', kid! Let's keep on rockin'!"

Sonic and Tails zoomed across the log bridge, only to run into another squad of SWATbots a couple ways down. However, these bots also proved ineffective in stopping the duo, who kept jumping and jamming their way deeper and deeper into the cave. Sometimes, the SWATbots would be so numerous that their laser fire would briefly light up the cave. Of course, that was all it was to Sonic: a pretty light show. At one point, Sonic nearly tripped on an improperly-pounded railroad spike and almost fell into a pit of spikes.

"Are you all right?" asked Tails.

"Yeah, but I had this really freaky thought…" replied Sonic.

"What?"

Sonic pointed at the pit with his hand. "When I looked down at those spikes, it occurred to me: what if I was immortal? I probably woulda been stuck down there forever!"

"Sonic, where do you come up with this stuff?"

Sonic shrugged. "I dunno."

Without further question, Sonic and Tails kept running, hardly encountering any more surprises barring a few of those swinging maces that were similar to what Sonic had encountered in Rusty Ruin Zone and Labyrinth Zone. Ol' Blue wondered why those were even in a mine, but soon chalked it up to overzealous security system designers and kept moving. Eventually, the whole cave began to rumble.

"Sonic, what's going on?"

"There better not be ANY more lava comin' at us!"

Fortunately for Sonic and Tails, there would be no lava coming up at them at this moment. Unfortunately, a bunch of debris was falling from the low ceiling in this section, which manifested in the form of rocks and stalactites. The sheer amount of crap that was coming down was enough to overload Sonic's Hedgehog Sense, confusing him as to which way he should even run. He chanced it and hoped for the best, which saved his life. However, there was still one matter to attend to…

"Ah, I see you've decided to catch up, Sonic and Friend!" said Robotnik, whose Eggmobile now sported a large drill on each side and two fog lights on top.

"Look, let's cut the crap and tell me how you're gonna blow it this time!" said Sonic.

"Blow it? Why, I should hardly think that my Egg-O-Matic Drill Craft will do such a thing!"

"Oh yeah!?" said Tails. "Well, Sonic and I are gonna win, just like last time!"

"SILENCE! You'll do no such thing!"

With that, Robotnik charged at Sonic and Tails, who jumped over the drills and gave the Eggmobile a good bit of ass-kicking. However, Robotnik had the drills pointing upwards in short order and burrowed through the ceiling. As a result, more debris fell down, and once again, the stress placed on Sonic by his Hedgehog Sense nearly caused him to shut down.

"SONIC! Watch out!"

Tails grabbed Sonic and pulled him out of the way just before a stalactite could impale him. Big Blue shook his head.

"Thanks, Tails! I thought I was done for!"

"You're welcome, Sonic!

Soon enough, Robotnik came back down, and the debris stopped. With that, the Doctor attempted another charge at Sonic and Tails, only for them to land a few more hits on the Eggmobile than he would've liked. This time, when he attempted to drill upwards, Sonic and Tails hit him a couple more times, thereby causing the drill attachments and fog lights to explode.

"Jeez, you're slippin', Robuttnik!" said Sonic. "That was less of a challenge than the last machine ya tried on us!"

"CURSE YOU!" said Robotnik. "Were it not for the slow drilling speed, you and your friend would've been on my dinner plate by now!"

"Yeah, whatever! On to the next round!"

"Yeah!" said Tails.

Robotnik growled and uttered a series of inaudible curses as he attempted his escape. Naturally, Sonic and Tails followed.

Criticism is gold. Negativity and nitpicking are pyrite.