[100%] 
Here's my idea...
Intro.
Sometime following the events of Sonic Adventure 2, Dr. Eggman hit on an idea. If he couldn't rule the world, maybe he could build his own. He began planning the construction of an underground empire completely isolated from the rest of the world, where his robotic creations would be his loyal citizens, where he could invent and live like a king without fear of interference. It was the ultimate retirement plan, but he knew he couldn't stick around, or else the project might be discovered. Thus he created an artificial intelligence system based off of himself (similar to GLADOS in the Portal series) to watch over things while he was out trying to conquer the real world. With this system in place the empire continued to expand, and many advancements were made to the doctor's creations and the technology used in their environment. Now, Eggman's finally ready to retire, but his artificial counterpart - now known as Lord Robotnik - doesn't feel like stepping down. As it turns out, he’s grown tired of being limited to the artificial and is bent on ruling the real world. After coming into the possession of a chaos emerald some months before, he made it his goal to figure a formula for creating an exact duplicate with the same wavelength and properties (sound familiar, SA2?
). If successful, he plans mass produce it and build an entire army of chaos emerald powered robots.
In desperation Dr. Eggman sends a robot to the surface with a message revealing the whereabouts of his secret entrance, addressed to none other than his arch nemesis, Sonic the Hedgehog...
Game-play:
(1) Zones
You (Sonic) begin your adventure in the Half-Life Zone, essentially the underground empire’s place for dumping broken, outdated creations. Once you find Eggman’s pod (Sonic, Tails’, and Knuckles’ mobile base of operations) your mission is fairly straightforward. The basic goal is to find the exit portal and travel to the next zone, and eventually reach Lord Robotnik’s control center in the final Zone.
The individual areas within each zone would vary in style. Many would have an adventurous feel though with a general point A to point B progression, similar to action stages in Sonic Adventure. A few would be more open and hub-like, though they aren’t really hubs (these areas are often the most heavily guarded). As you get into later zones, areas start to become less straightforward in design, with interconnecting pathways and an almost Metroid-esc complex aesthetic to their overall composure.
(2) Rings
One departure from the traditional formula is in the role of rings. In the past they were only helpful to you as a means of protection. Down here, rings have been converted into a fuel source which the entire robot population uses, so don’t expect to find any just floating on the path in front of you. You start the game with about 100 rings (50 on hand, 50 in reserve), and gain more by defeating robots, through hacked fuel stations, or in hidden ring stashes. In battle, the fuel a bot has left when destroyed determines what you get from their defeat. Each time their shields deflect an attack or they use their weapon against you, a small amount is depleted. In general, quickness and good timing are key to netting the most rings. Also, you don’t have a set amount of lives per-say, but when you do run out of rings in the field and black out, rings are taken out of the reserve collection for you to have when you wake up at the last checkpoint. If none are left in stock when that happens then it’s game over.
(3) Characters & Missions
The basic goal may be to find the exit to the next Zone, but gaining access to it is rarely as simple as just following the path. Sonic, Tails, and Knuckles would each be playable characters, and though missions would not generally require using one in particular, each has personal strengths and abilities which are better suited for some situations than others.
Sonic – He’s got reasonably powerful attacks, can roll through tight spaces, and he’s really fast. Enough said.
Knuckles – As usual he can glide, climb walls and burrow through the earth to find hidden chamers. He’s also so strong that small bots only take one direct strike to be destroyed. Unfortunately he is the least nimble and is almost always being chased and ambushed by Robotnik’s forces. Still, this combination of the enemy’s easy destruction and large numbers actually can be helpful if you’re looking to score a lot of rings.
Tails – A return to on-foot/airborn game play, though more stealthy. He can’t put up much of a fight in the conventional sense, instead making use of a multipurpose wrench-like gadget and his surroundings. The device does minimal damage when used as a melee weapon, but can also send out a pulse causing robots to momentarily shut down, giving him a chance to reprogram it to fight other robots. What makes him useful is his ability to hack ring fuel sources, and hidden control centers, making things easier for everyone in the long run.
So, after all that, what do you think?
Intro.
Sometime following the events of Sonic Adventure 2, Dr. Eggman hit on an idea. If he couldn't rule the world, maybe he could build his own. He began planning the construction of an underground empire completely isolated from the rest of the world, where his robotic creations would be his loyal citizens, where he could invent and live like a king without fear of interference. It was the ultimate retirement plan, but he knew he couldn't stick around, or else the project might be discovered. Thus he created an artificial intelligence system based off of himself (similar to GLADOS in the Portal series) to watch over things while he was out trying to conquer the real world. With this system in place the empire continued to expand, and many advancements were made to the doctor's creations and the technology used in their environment. Now, Eggman's finally ready to retire, but his artificial counterpart - now known as Lord Robotnik - doesn't feel like stepping down. As it turns out, he’s grown tired of being limited to the artificial and is bent on ruling the real world. After coming into the possession of a chaos emerald some months before, he made it his goal to figure a formula for creating an exact duplicate with the same wavelength and properties (sound familiar, SA2?
). If successful, he plans mass produce it and build an entire army of chaos emerald powered robots.In desperation Dr. Eggman sends a robot to the surface with a message revealing the whereabouts of his secret entrance, addressed to none other than his arch nemesis, Sonic the Hedgehog...
Game-play:
(1) Zones
You (Sonic) begin your adventure in the Half-Life Zone, essentially the underground empire’s place for dumping broken, outdated creations. Once you find Eggman’s pod (Sonic, Tails’, and Knuckles’ mobile base of operations) your mission is fairly straightforward. The basic goal is to find the exit portal and travel to the next zone, and eventually reach Lord Robotnik’s control center in the final Zone.
The individual areas within each zone would vary in style. Many would have an adventurous feel though with a general point A to point B progression, similar to action stages in Sonic Adventure. A few would be more open and hub-like, though they aren’t really hubs (these areas are often the most heavily guarded). As you get into later zones, areas start to become less straightforward in design, with interconnecting pathways and an almost Metroid-esc complex aesthetic to their overall composure.
(2) Rings
One departure from the traditional formula is in the role of rings. In the past they were only helpful to you as a means of protection. Down here, rings have been converted into a fuel source which the entire robot population uses, so don’t expect to find any just floating on the path in front of you. You start the game with about 100 rings (50 on hand, 50 in reserve), and gain more by defeating robots, through hacked fuel stations, or in hidden ring stashes. In battle, the fuel a bot has left when destroyed determines what you get from their defeat. Each time their shields deflect an attack or they use their weapon against you, a small amount is depleted. In general, quickness and good timing are key to netting the most rings. Also, you don’t have a set amount of lives per-say, but when you do run out of rings in the field and black out, rings are taken out of the reserve collection for you to have when you wake up at the last checkpoint. If none are left in stock when that happens then it’s game over.
(3) Characters & Missions
The basic goal may be to find the exit to the next Zone, but gaining access to it is rarely as simple as just following the path. Sonic, Tails, and Knuckles would each be playable characters, and though missions would not generally require using one in particular, each has personal strengths and abilities which are better suited for some situations than others.
Sonic – He’s got reasonably powerful attacks, can roll through tight spaces, and he’s really fast. Enough said.
Knuckles – As usual he can glide, climb walls and burrow through the earth to find hidden chamers. He’s also so strong that small bots only take one direct strike to be destroyed. Unfortunately he is the least nimble and is almost always being chased and ambushed by Robotnik’s forces. Still, this combination of the enemy’s easy destruction and large numbers actually can be helpful if you’re looking to score a lot of rings.
Tails – A return to on-foot/airborn game play, though more stealthy. He can’t put up much of a fight in the conventional sense, instead making use of a multipurpose wrench-like gadget and his surroundings. The device does minimal damage when used as a melee weapon, but can also send out a pulse causing robots to momentarily shut down, giving him a chance to reprogram it to fight other robots. What makes him useful is his ability to hack ring fuel sources, and hidden control centers, making things easier for everyone in the long run.
So, after all that, what do you think?
Did I mention the game taking place in space? Anyway, I did not mean that all the zones would be dull and rusty, I just threw my idea for the first zone out there as a starting point. The empire may be artificial, but that doesn't mean it can't be made with some style. 
