Grimrock

Any idea on how to trigger light? like you step on something and light turns on

For light source objects, from the scripting reference:
"
LightSource:activate()
Turns on the light source.

LightSource:deactivate()
Turns off the light source.
"

You can do this just by adding a button or a lever or a pressure plate and connecting it to the light source in the editor, so no actual scripting is required.

But I suppose it is a bit different for completely scripted lights, not light-source objects. Someone probably knows them well around here, though.