You can do it right, you can do it pointless and gaudy.
One of our customers had his TMNT game all the metal powdercoated green, green leds around the speakers, green acrylic to show up under the slingshot plastics, etc...
He had Green LED's under the game, and more importantly, behind the game.
You would approach the machine and it was making the whole corner of the room glow.
It was a nice effect.
On the other hand, an ACDC Luci had a couple of strips of red LED's under the game... didn't do too much for it.
Whatever you do, power your LED's external to the game power supply. No sense adding the opportunity for your add-on LED mod to take down the entire game.
And don't clip in to power using alligator clips. (shudders)