Based on the concept by raymoohawk: http://raymoohawk.deviantart.com/art/octaminator-528415081
Earlier I posted the high-poly version of this character; I recently worked at optimizing it, with baked textures from the high-poly. This version will actually fit in a real-time game engine.
Model + rig. Auto-IK is enabled, you can just grab bones and move them to animate the tentacles and arms.
Included: Model, rig, walk cycle animation, Diffuse and Normals textures. Both the .blend and the fbx .zip have all of these.