Basic Health Bar

1.  Render Engine: Blender Game
  • Info menu >> Render Engine box >> Blender Game
  •  There are menus that are only available when the Blender Game render engine is selected.
2.  Viewport Shading: Texture
  • 3D View menu >> Viewport Shading box >> Texture
  • Texture Viewport Shading renders the game objects with the textures you add.
3.  Material Shading: GLSL
  • Properties menu >> Render button >> Shading tab >> GLSL button
  • Also works with Material Shading: Multitexture
4.  Enable GLSL settings
  • Enable Shaders
  • Enable Shadows
  • Enable Lights
  • Enable Color Management
  • Enable Ramps
  • Enable Nodes
  • Enable Extra Textures
  • GLSL settings appear only when the Render Engine: Blender Game is selected. 
5. Add a new scene
  • Info menu >> Scene box >> + (plus) button >> New
  • The new scene will be used as an Overlay Scene
  • The health bar will be located in the Overlay Scene