Sonic the Hedgehog: Spinball (known in Japan as Sonic Spinball) is a hybrid 2D platformer/pinball video game developed by Polygames and published by Sega for the Sega Genesis on November 23, 1993. Players control Sonic the Hedgehog as a pinball (also controlling the various flippers around the stages), as he ventures through each of the four stages while collecting Chaos Emeralds and defeating the boss machines of Dr. Robotnik.
The game is one of the two games to make use of elements from both the Sonic the Hedgehog and Adventures of Sonic the Hedgehog cartoon series (the other game being Dr. Robotnik's Mean Bean Machine). The story involves Sonic infiltrating Dr. Robotnik's diabolical lair (the Veg-O-Fortress) on Mt. Mobius (thwarting his latest plan to turn the animals of planet Mobius into robots). This time, he must make use of Dr. Robotnik's new Pinball Defense System to navigate the lair.
The game was later ported to the Sega Game Gear (on September 1994) and Sega Master System (Europe only on January 1995) by SEGA IDD.
There are four levels. In each level, the player has to collect all Chaos Emeralds to unlock the boss room. Defeating the boss clears the level. In between each level, players can enjoy bonus stages that consist of Sonic himself playing an actual pinball machine with three lives to complete a challenge, and which have slightly different physics from the main game. Each Bonus Stage plays at a specific time and do not have to be completed; even if the player loses at the Trapped Alive stage after completing the first level, they will still proceed to the Robo Smile stage after completing the second.
After getting shot off Tails' plane in the intro movie, Sonic finds himself at the very bottom of the Veg-o-Fortress, a series of caves and sewers which have become polluted by toxic waste thanks to Robotnik's equipment. Most of the tables in this stage have safety mechanisms; the lowest one has a platform beneath the flippers from which Sonic can jump back up into the action (don't linger too long though, or you'll be eaten by a robotic sea monster!). Other tables feature a barrel floating in the river of lethal slime beneath the flippers, which Sonic can use as a makeshift boat. Once all Emeralds have been collected and the boss room opens, however, these barrels begin to move, pushing up the difficulty a notch. The boss of the level is the Robotnik-faced Scorpius, who leaks surprisingly un-harmful green goo from his tail, and is actually ridiculously easy to defeat.
Bonus Stage: Trapped Alive
In the first Bonus Stage, Sonic plays a machine containing seven miniature prison cages which hold representations of innocent animals and friends of Sonic. Sonic must hit each cage with a ball several times in order to break it and free the prisoner inside. However, a miniature Dr. Robotnik in his floating boss ship moves back and forth between the bumpers and the cages, attempting to block the balls and send them down the gutter. Once all the prisoners are free, hit Robotnik one more time with a ball to destroy his ship and win the stage. As in all Bonus Stages, you get three balls (lives) to complete the task, which does not reset when you lose a ball. In addition, Bonus Stages allow the player to "bump the machine" by pressing all bumper buttons at once, though this can Tilt the game, forcing them to lose their current ball. Notably, while the prisoners include Miles "Tails" Prower and assorted random animals, they also include Princess Sally Acorn, Bunnie Rabbot, and Rotor Walrus, characters from the Sonic the Hedgehog animated series; these cameos in Sonic Spinball are the only time characters from the show have appeared in an official game.
This stage is an energy plant where Robotnik transforms the heat from rivers of hot magma into power for the rest of the Veg-o-Fortress, so relatively common pits of lava are the greatest danger here. There are steam jets and pistons that Sonic can use safely, and several parts of the stage feature doors that the player needs to hit several times before they open, as well as helpfully-placed "shotguns" which fire Sonic directly into the doors. A pressure dial gauge ensures that the player does not advance before collecting all the emeralds. The boss is the Robo-Boiler, the artificial intelligence which oversees the Powerhouse. Its weak points are the cluster of Robotnik heads inside its main body, and while the Boiler itself is defenceless, it will summon an endless swarm of flying Clucks to get in the way and prevent Sonic from getting inside.
Bonus Stage: Robo Smile
In the second Bonus Stage, the grinning face of Dr. Robotnik moves back and forth on the table, and players must smash all four of his teeth by hitting them repeatedly with the ball. Players can also earn points for hitting the back of Robotnik's head, for getting the ball into his mouth by shooting it into a gap left behind by an already smashed tooth, and for hitting the targets lining the back of the table. Sonic earns a nice bonus every time he hits all three targets.
Dr. Robotnik would never make a lair this big without including a roboticization machine for transforming innocent animals into mindlessly obedient Badniks, and the Veg-o-Fortress is no exception. In 'The Machine', Sonic must carefully make his way through the twists and turns of the incredibly elaborate, unusually enormous roboticization chamber, here called the Veg-o-Machine. But be careful, below the flippers is a set of grinding gears which poses the primary threat in this level. Teleporters abound, and the elevator sections really challenge the player's aim. At the centre of The Machine is an array of cages to bust. Freeing all animals is not required, but it does award the player a nice bonus. The boss of this level is the actual chamber where animals are roboticized; Sonic must get inside through the exit port in order to bust up the machine, but first he must destroy the tubes feeding captured animal prisoners into the chamber, because the constant flow of robots blocks the exit otherwise. Which is just fine, since he was going to do that anyway.
Bonus Stage: The March
The centre of the third Bonus Stage's table has an Egg Prison on it, the chamber found at the end of every level of Sonic the Hedgehogs 1 through 3 that frees imprisoned animals when a button on top is pressed. Since the ball in the Bonus Stage can't leave the ground, you're going to have to do this the hard way and smash all the side panels to destroy the Egg Prison. But robotic duplicates of Scratch (a character from The Adventures of Sonic the Hedgehog, another animated series) march endlessly in a circle around the Prison, and you'll need to destroy them first if you want to get to the cage.
Boss: Robotnik's Ship
The Lava Powerhouse has been shut down, rendering the power level wildly unstable, and the Veg-o-Machine has been utterly destroyed, cutting off robotic reinforcements. Sonic's meddling has left the Veg-o-Fortress on the verge of collapse, but Robotnik still has a few Badniks up his sleeve as well as a backup plan, to flee in a rocketship into space. Sonic must pursue Robotnik through his space hangar and stop him from escaping. Despite this setting, there is no time limit, however this stage is by far the most merciless. A whole sequence of switches need to be triggered to activate the kickback for one of the deadly outlanes, and it is possible to fall out of the boss room with Robotnik's escape craft, requiring the player to fight their way back up before they can continue the battle.
Secret Bonus Stage: Cluck's Defence
Although the game ends when you complete the Showdown level, and there is no proper fourth Bonus Stage, a hidden Bonus Stage can be reached during any of the game's four levels: if Sonic collects every ring on a level, then circles of swirls will open up throughout the level (similar to the swirls leading to bonus stages that appear above Checkpoints in Sonic's platforming games). Jumping into the swirl here leads to a special Multiball Bonus Stage, where all three balls are in play at once. The actual objective is to destroy a crab robot in the back row by hitting him many times with the balls. However, two defensive Cluck robots move back and forth in front of him in the way Robotnik did in the Trapped Alive stage. Destroy the crab robot to win the stage, and you'll get a huge bonus to your score and be returned to the level you just left.