Turn On Forbis's ! Shaders With Iris or OptiFine

Forbis's ! Shaders is a shader pack, so you need a shader loader to run it. Use Iris (on Fabric or Quilt) or OptiFine. The pack does nothing without one.

Put the pack where the loader can find it

1. Launch the game once with Iris or OptiFine installed. This creates the shaderpacks folder inside your .minecraft directory.

2. Place the Forbis's ! Shaders file in the shaderpacks folder. Leave it zipped.

3. Do not put it in resourcepacks. This is the most common mistake. A shader pack in that folder is either ignored or shows up as a broken resource pack.

Select it in game

• Iris: Go to Options → Video Settings → Shader Packs. Click Forbis's ! Shaders, press Apply, then Done.
• OptiFine: Go to Options → Video Settings → Shaders and click the pack in the list.

The screen may freeze for a moment while the shaders compile. This is normal.

Check that it worked

Stand near a light source at night or underground. You should see two changes:

• Colored lighting across nearby blocks.
• A soft vignette that slightly darkens the edges of the screen.

Everything else should still look like vanilla Minecraft. That is intended, because the pack keeps the classic look.

If nothing changed, reopen the shader menu. Confirm the pack is highlighted and that shaders are switched on. Iris has an on/off toggle in that menu.