The original game doesn’t support mods natively. You must use HedgemodManager (not the old SonicGLVL or other deprecated tools). Make sure you’re on the latest version.
Some mods need to be above or below others. For example, a model swap usually goes above a level retexture. When in doubt, disable all mods and enable them one by one to find the conflict. sonic generations mods not working
Many gameplay or visual mods require SonicGMI (Generations Mod Injector) or CodeLoader . Read the mod’s description carefully. If it says “requires CodeLoader” and you don’t have it, the mod will silently fail. The original game doesn’t support mods natively
Try renaming or temporarily moving your dxgi.dll or d3d9.dll files (some graphics wrappers interfere). Also, make sure you’re not running the game through Big Picture Mode—launch it directly from Steam or the mod manager. Some mods need to be above or below others
Once everything clicks, Sonic Generations becomes one of the most moddable 3D Sonic games out there. Don’t give up—fixing the mod loader is a rite of passage.