Well-supported level design tools (such as Zone Builder) that allow easy creation of your own custom stages. (See SRB2 Wiki: Level Design for more info.) Flexible mod support via Lua scripting or Sonic Object Configuation system - allowing new items, enemies, bosses, scenery effects and (...
Online random gameplay footage with clips from Greenflower Zone, a Special Stage and Techno Hill Zone. This was recorded with a WSAD + Mouse setup (common to traditional FPS games), using the (very beta!) OpenGL hardware rendering. As such, there may be graphical mishaps here and there (...