Tile by tile lighting - Shader/alpha values/lightmap?

Hi guys. I know this sort of question has been asked over and over but I can’t seem to find any information on what i’m specifically looking for.

I want to create a lighting system where the lighting is not exactly smooth. Each tile around the player will be lit with a slightly different alpha value and give a very block-y feel to the lights. Much like the image below:

http://soapquest.googlecode.com/svn/trunk/screenshots/SoapQuest%201024%201.jpg

I have a few ideas in mind but i’m not sure if they are the correct way of doing things. My first idea was to simply change the alpha value on blocks around the player but this seems expensive on the CPU as it will have to update every frame. My second idea was some kind of lightmap, where I blend the image over the player using OpenGL and a shader but I don’t know if this will give me my block-y effect.

Anyone every done any lighting like this before? :slight_smile: