I've always felt like both Sonic and Mario games were a little too conveniently simple to overcome. Most stories start with everyone Sonic or Mario knows being ruthlessly kidnapped, without a hair on their head actually coming to harm in the process.
Robotnik and Bowser create obstacle after obstacle, leading their enemy down a set path from the safety of their own home to a convoluted fortress of doom. If you follow the canon of the games then Sonic and Mario always win, either single handedly or with the help of their friends. There is always a way if they just figure it out and use the tools around them. More often than not they also kill a mythical monster of some kind and clear out the world's undesirable inhabitants.
The question is, who the hell is leaving extra lives, fast shoes, fire flowers, and magic objects for either hero to use?!
Only Robotnik has the brains and resources to create machinery on Mobius, where Sonic lives. So every device you come across that leads you to become invincible, or takes you to the hidden Chaos Emeralds, has been designed to help Sonic reach him. The same in The Mushroom Kingdom. Those blocks loaded with power ups, and magical switches, are surely placed there for Mario, his friends, and only them. If you unleash a mushroom, fire flower or feather and a Goomba touches it, they don't gain the powers Mario and Luigi get. Certain areas are only reachable if Mario finds and utilises a specific tool gifted to him near the point at which he needs it. This isn't some miracle happenstance, like a dock leaf growing near a stinging nettle to help you cure the burning sensation. It has to be divine intervention of some kind.
This is where I would collide both worlds and blow the whole story apart with a grand reveal, and this is how I would do it:
The game begins, you're met with a brief introduction. Sonic has, yet again, cornered Robotnik in his Death Egg. Mario is closing Bowser down on a bridge, surrounded by lava. Both characters enter their final battle, and you - the player - are forced to pick which hero you wish to play as from here on out.
You select Sonic, and tee off a genuine end game boss battle along the same lines as Sonic 2 and 3 offered with the giant Robot stomping around trying to destroy you. At this stage Sonic already has the Chaos Emeralds, he's golden and it doesn't take much to figure out the route through the doctor's evil plans. After the required amount of successful hits, you're met with the usual victory ending you've come to expect from Sonic games. Everything is exploding, the ship is crash landing and like always you're heading for the door. Except this time, as you're jumping for safety and inexplicably surviving a fall from space thanks to the awesome power of the Emeralds, you see your oldest foe is still alive and kicking. He's making an escape and he doesn't seem that phased. In fact he's laughing!
"You really did it this time, Hog! Hoo hoo yes..." He's floating along in his trademark Egg Mobile, surrounded by a forcefield which looks eerily like the invincibility power Sonic used to overcome a gauntlet of horrific spikes a few days/levels previously.
"Aw C'mon Eggman, just retire already. I've beaten you so many times now it's barely even a challenge..." Sonic is still falling, but he knows Tails will catch him eventually, he always does.
"Is that so? Perhaps you're finally ready..." Robotnik is getting closer. Normally he flees as fast as he can, giving Sonic at least 2-3 years before he tries anything new.
"Ready to beat you one last time old man..." Sonic prepares for whatever trick Egg man has up his sleeve.
Before he knows it however, he's zapped with a mysterious ray, immediately the Gold seeps from his skin, turning him the usual deep blue colour. He flops powerlessly, falling faster, like a dead weight. Robotnik scoops him up with one of his gadgets and flies into the distance.
Some time later:
As Sonic comes too, he wonders what happened. He doesn't seem to be trapped, he isn't imprisoned. As he gathers his senses he see's a human passed out in a bed on the other side of the room. He gets to his feet, feeling a little dazed, and walks over to the bedside of his fellow captive.
He lays a hand on the side of the bed, deciding whether or not to wake his roommate. There haven't been that many humans in Mobius over the years, and the men tend to try and kill Sonic every chance they get.
Before he gets a chance, the door crashes open, waking the man anyway. A giant lizard enters, breathing heavily with a growl that suggests he's almost as unfit as Eggman.
"Time to wake up Plumber, you two are needed outside right away."
While he waits for the human to react, he holds out a hand to Sonic.
"The name's Koopa, King Koopa, you can call me Bowser."
Sonic hasn't met many lizard people but this guy seems alright, he hasn't tried to kill anybody in the short time they've shared the same room. He shakes the King's hand and follows as he is ushered towards the door.
"Whose the hat guy?" Sonic asks.
"Me? Mario!" the man calls out, as he rushes to follow from behind.
"Never heard of you..." Sonic replies as the door closes behind them.
Sonic and Mario enter a large dark room, there's a spotlight in the middle and they're pushed towards it. Koopa steps aside and disappears into the shadows before reappearing on one of two thrones placed high above the ground, looking down on the heroes as they wait to see what happens next.
With a loud cough, Robotnik enters the room and takes a seat alongside Bowser, his grin is huge and unnerving.
"What are you up to Eggman?!" Sonic shouts.
"SILENCE" a third voice fills the room, but the owner does not come forward.
"ALL WILL BE EXPLAINED" it finishes.
Robotnik starts, "You'll be pleased to hear you have both passed."
"Passed?!" Mario replies.
"Our challenges..." Koopa responds.
"Challenges, you guys are evil!" Sonic yells, getting ready to spin his way out of there as soon as he figures out an exit.
"Ohh hoo, Evil? What did we ever do that was Evil?" Robotnik asked.
"You kidnapped thousands of animals, you poisoned our world, you flooded an entire ocean with Oil!" Sonic replied in disbelief at Robotnik's apparent amnesia.
"Nonsense! I gathered those animals to protect them from the trials you had to endure. You let them free when things were safe, I even set the obstacles to explode if you pressed the button, removing any danger from harming the animals."
"But what about the huge machines, the oil ocean, the weapons of mass destruction, you stole the emeralds time and time again!"
"The machines? We need them to deliver supplies where you're going, the threats were there to test you. The oil? That wasn't strictly me, ...an, unfortunate accident that we're working to reverse with some purification plants. No animals were harmed, we gave most mechanical suits to keep them safe. The Emeralds? We separated them time and time again only for you to join them back together whenever you solved our puzzles. They weren't exactly easy to solve."
"I can't believe it, I won't believe it. You're Egg Man and you're bad." Sonic's head was starting to spin.
"No, I was sent here to test you. We made you fast. We've put you through your paces, given you new tools and new skills to overcome increasingly narrowed odds. You've done well to get this far, many of our other test subjects died almost instantly! We retired the early prototypes, you and The Plumber here were our most reliable heroes."
"Where do you think all of these 'power ups' came from?" Koopa offered into the debate.
"Huh, I'd never thought about it I guess..." Sonic replied, scratching his head a moment. Could it be true? He did always seem to find a bubble sphere when he needed to breath underwater. It did seem odd that he could often make his way up tall obstacles merely by bouncing off of the various robots Eggman had laid out to defeat him.
"But why? You took Amy, hurt Tails, sent two Silver Sonics, Shadow and countless other villains to take me down. How was that helping me?!"
"All incentives to push you to your limit. Shadow was made to replicate you. A contingency plan...that had some draw backs. As for why? Well the two of you are the only survivors of a long experiment to find the very best of our worlds. Many others have been tested. All have died. The two of you are our best hope of success."
"TIME IS RUNNING OUT" the loud voice boomed again, startling the four of them.
Sonic turned his head towards Mario, who had been rather silent up to this point. He responded with a shrug and a nod, with a look of determination.
"What's the plan then?" Sonic asked. Working with Eggman felt extremely unsettling.
With a loud click somewhere in the darkness, a pair of bright circles appeared beneath Eggman and Koopa. One red, One blue.
"GO...NOW" the voice commanded.
"Who or What are we fighting?! Where are we going? We aren't prepared for this! Why are there two doors?!" Sonic called out, directing his questions more to the voice than at Eggman or Koopa.
"YOU WILL LEARN" the voice replied.
"We've done what we can to protect you both, the rest is in your hands though. If we can get your allies out to you in time we will, but don't expect anything unless you're able to make some ground and give us a foothold." Koopa Explained.
"You're both going in alone, and will attack from two sides of the same planet. You should be familiar with many of the threats and landscapes you encounter as our limited intelligence has allowed us to model your training to what you can expect when you're there." Robotnik added.
"THE PORTALS ARE CLOSING" they start to dim and crackle.
"Please, I know it is hard to believe but it is the truth. We need you." Koopa offered, trying to convince them both that they must listen.
"Fine, I've had a pretty long life for a super fast Hedgehog..." Sonic said, looking expectantly at Mario.
"Meh, Okay.." Mario sighed, aligning his hat, ready to move.
"RUN" the voice commands.
Sonic set off with a bolt of energy as fast as he could, as he reached the blue circle he glanced back to see Mario still starting his jog towards the Red portal. As he began to go through, Blue light surrounded him, and before he could even blink he was in a new world.
Nothing looked familiar...
Join Sonic in his biggest challenge yet - A world much like Mario's with various similar, but slightly different, creatures to fight through. Use mushrooms, flowers, feathers and so forth to help Sonic navigate obstacles and defeat the mystery enemy.
Play as Mario, arriving in an unusual land of twists, loops and springs, with robots and spikes everywhere. Can he struggle through with various forcefields and rings to aid him?
Oblivious to the mixup, Koopa and Robotnik do all they can to assist Sonic and Mario, sending Luigi to assist his brother (and instead finding Sonic) and dispatching Tails to help Sonic (Mario) navigate the difficulties of this alien world.
Like all good games, the replay value comes from New Game + where with some technical wizardry the portals are fixed before our heroes set off, meaning Sonic is back in his element and Mario has his familiar power ups to fight with, creating a new challenge with levels that their counterparts could not complete in quite the same way.
What do you think? Should Nintendo be making this for the Switch? Would you play it? Let me know in the comments!