The final Halo 3 Easter Egg has been found seven years after the game was released. Back in 2012, Bungie confirmed the existence of this Easter Egg and revealed that it will work only on specific day.
“There is one Easter egg in Halo 3 that I don’t think anyone has found – I stumbled across it in code a while back. It only happens on a specific day … so good luck.”
Today, Teambeyond.net revealed how to experience this Easter Egg. When you press down on both thumbsticks during the loading screen on December 25, you’ll be shown a wider view of the Halo ring with the words “Happy Birthday Lauren!” on the ring’s surface. This Easter Egg was done by programmer Adrian Perez dedicated to his wife as a birthday gift.
Adrian Perez claimed his proudest moment at Bungie was “showing my wife the Easter egg I put in the halo 3 loading screen for her – the one that nobody has found yet.”
Source: Teambeyond.net via: IGN