Sonic Robo Blast 2, abbreviated as SRB2, is a computer fangame based on the Sonic the Hedgehog series. 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, such as collecting rings, dropping rings when damaged, running very fast, bouncing off springboards, etc. 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 Sega 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.
So, this gives the basic jist of what the game is. If you're into good Sonic fangames, or Sonic in general, I'd advise to give this game a go. The controls are great, and the level design is amazing, especially in the latter levels, showing what you can do with the Doom engine, producing one of the firts 3D Sonic fangames, if not also the bets. As also mentioned in the quote, being that it's made with the Doom engine, it makes customization extremely easy. There's quite a few characters and levels made for SRB2, and there's even an official level design contest. So Iin my opinion, this is really one of the best Doom mods and Sonic fangames out there.Official WebsiteForumsWiki