Lights off definitely  or at least dimmed or low lighting in the room. I sometimes go down to the pinball dungeon in the evenings and turn ALL the games on and turn the shed lights off, turn the music up and play a few games!! Much better atmosphere for a gameroom i reckon, with low lighting or even just the lights from the pins lighting up the room 

A mate of mine who has a few pins, likes to have a lamp sitting beside the game shining done ON THE PLAYFIELD when he plays them    he does this with about 3 of his half dozen or so games and it really bugs the shit outta me.. i mean i'll start a game at his house without the lamps on and he'll come along and turn the bastard on when he wants a game against me  i just find it distracting.. maybe its a ploy to make me play bad so he can beat me i guess