You can use iCUE to set up a custom lighting effect when launching an app using the "Launch Application" key assignment  on an iCUE-compatible mouse or keyboard.

Make sure that your iCUE software is updated to the latest version.

NOTE: The option to set up lighting effects is only available when configuring a lighting type under the Custom tab. Preset lighting effects will not work.

Setting up the custom lighting layer

The first step is to set up the custom lighting layer that you will use. To do this:

1. Open iCUE.
2. Select the keyboard or mouse you want to assign the effect to.
3. Click Lighting Effects.
4. In the Lighting Layers section on the bottom left, click the + button.
5. In the Lighting Type section, select the lighting effect you want to use.
6. Make sure to set how long you want the lighting effect to last (in seconds).
   
   
   
7. Once you are done, save the lighting layer to the Lighting Library.
   

Assigning the lighting effect

After you have created your lighting effect, the next step is to create the Key Assignment that will trigger the lighting effect. To do this:

1. Select Key Assignments in the menu of your mouse or keyboard in iCUE.
2. In the Assignments section, click the + button.
3. In the Assignment Type section, select Launch App.
4. In the Key section, select the key you want to use to trigger the lighting effect.
5. In the Launch App section, select the app you want to launch when using the Key Assignment.
   
   
   
6. Click the Advanced tab on the right side of the screen.
7. Select the lighting effect that you have created earlier to assign it to the Key Assignment.
   

Once you have set the lighting effect, the effect will play whenever you launch your selected app.