So what's going on in Light in the Darkness? The Totems are (apparently) a race of little gumdrop-shaped creatures that emit light. No need to judge, though. Their offspring have gone missing, and you have to use their luminous powers to spot the youngsters.
Simply move the Totems around the level to shine the light on all the baby Totems to complete the level. Sometimes you'll have to combine different colors of light to make the right shade to illuminate the youngsters, but also keep in mind the stars have to be lit up to unlock more levels. Then there are all sorts of obstacles, mirrors, lenses, and more to deal with. It gets pretty involved after only a few levels.
Should you find yourself at a loss, there's a hint system built into Light in the Dark. It'll cost you, though. The game itself is $2.49, but the IAPs are for hints. You don't have to use those, of course.