To get this achievement, you have to light all of the places that Teku can use to light his candle. You will be setting light to other objects not included in the list below, but because they can't be used as light sources, they don't count. The sources are:PROLOGUE
Sources 1 and 2: The torch by the burning fence and the candle outside the hut.ACT 1
Source 3: The totem by the water pump.
Source 4: The candle at the start of the level.
Source 5: The candle at the foot of the windmill.
Source 6: The candle in the room at the top of the windmill.
Source 7: The totem above the fat toad.
Source 8: The candle by the giant fish.
Source 9: The candle that triggers the light from the trapdoor in the last area of the level.ACT 2
As you have to turn all of these blue for another achievement anyway, I've listed them in order from when you create the blue flame.
Source 10: In the cave by the blue flame.
Source 11: The idol by the painter.
Source 12: The candle at the bottom of the ladder by the cave mouth.
Source 13: The candle in the tree trunk by the giant statue.
Sources 14 and 15: The lever at the bottom of the statue and the candle by the door into the area with the monkeys.
Sources 16 and 17: The lever at the top of the statue and the flame below the idol in the tower.
Sources 18 and 19: The candle above the save point and the candle to the right of the trapdoor.
Source 20: The blue flame in the basement room below the monkeys.
Source 21: The blacksmith's furnace.ACT 3
Sources 22 and 23: The torch in the middle of the town arches and the gargoyles by the door to the bath house.
Source 24: The save point above the entrance to the temple.
Sources 25 and 26: The pipe belonging to the green tribesman and the candle by the door in the basement of the temple.
Source 27: The candle on the top floor of the temple above Tezca.
Source 28: The altar in the temple.