The simplest way to provide portable light is to create a portable object and set its brightness property to a suitable level, e.g.:
Thing 'brass lantern' 'brass lantern' @mainCave
"It's an ordinary brass lantern, except you can't turn it off. "
brightness = 3
We shan't be making this lantern a permanent feature of the game, but if you want to experiment, by all means try it. You'll find that when the player character is carrying the lantern you can move around all the previously darkened areas easily, since the lantern now provides light. For some games in some situations this may be all you need. The other classes of light-providing objects we'll be looking at simply provide more sophisticated ways of adjusting the brightness property of (usually) portable objects.