It's fully possible, but you have to understand the limits of the HL engine or you will get extremely high r-speed maps or some really wierd crash could appear. And the textures in Radiant use shaders to describe the way they are rendered. HL does NOT support these shaders. There's a separate game packet for HL and I'll will post a tutorial on how to use it once I get rid of all my school work. However ANdy will be gone until next year so stay tuned and use good old WC until then.