Sonic Robo Blast 2, abbreviated as SRB2, is a fan game for Windows and DOS platforms. It is a 3D platformer developed by a group called Sonic Team Junior, using a modified version of the Doom Legacy source port of Doom, to allow for such things as optional analog control and true room-over-room (something not possible in the standard Doom engine), as well as the standard gameplay elements Sonic games are known for. It has been in the works since 1998 and is currently nearing completion, though several parts of the game are still missing.

Sonic Robo Blast 2 is closely inspired by the original 2D Sonic games for the Genesis and attempts to recreate a game with this style in 3D, though it also borrows elements from the current Sonic games, such as Sonic's signature Air Spin Attack. Entirely original to SRB2 is its Multiplayer mode, a variation of classic first-person shooter games with Sonic elements. Due to being built with a modified Doom Legacy engine, the game is also very easily customizable. Custom levels, characters and even source code modifications can be created with the help of external editors.

After Eggman was defeated back in the first game, he decides to take more time to reconsider his strategy, hiding away in an underground base for three months. All Eggman really had to show for this delay was a reduced robot army and a special battleship he built called the ‘Doomship’. He didn’t stand a chance against Sonic and his friends. Eggman’s space-radar bleeped as the Black Rock came within its range. Eggman thought nothing of it at first, until he realised that he had a new battlestation! From there he could attack the world, and launch robot armies without the fear of anyone retaliating against such a huge weapon. And with the Chaos Emeralds, the world would be begging before his knees to end the suffering and let him rule the planet. It was a perfect plan!

Eggman decided to quickly increase the amount of robots he was producing. World domination was within his grasp at last! He launched his Doomship a week later, full of robots to take temporary control of zones until he’d finished putting the final touches to his work on the Black Rock. They were also instructed to return any Chaos Emeralds they might find.

Sonic was enjoying his long overdue vacation. Without Eggman around, he and everyone else could relax whenever they wanted. Little did he know that today was going to be the end of it. Hearing Tails’ voice in the distance, Sonic rolled his eyes. It was probably a stray beach ball, thrown out into the sea. No doubt Tails wanted him to recover it. Tails arrived, and told him that there were robots attacking the Forest Zone. Before Tails could finish, Sonic was already a tiny dot on the horizon. The robots were simple Crawla robots, destroyed with minimal effort. Sonic looked up at the sky and to his horror, saw an enormous battleship, with its guns pointing at the Greenflower City. He had been tricked into a diversion! Without wasting time, Sonic rushed up to the Doomship, even though there was nothing he could really do.