To access the easter egg:

     1.  In  town,  head  to  the  Research  Center (or whatever it is
called), when you reach the steps (before walking up), turn 90 degrees
to  the  right. Walk straight for the gate with the blockades in front
of it.

     2. Go around the blockades and get to the gate itself. It has two
beams "locking" it shut.

     3.  If  you're  really  Trespasser savvy, you shouldn't have much
difficulty  climbing  up  to  gate. (keep jumping, and walking forward
until  you are at the top). Don't worry about falling off to the other
side,  there  is  one of those invisible boundaries here. You couldn't
walk off the wall if you wanted to.

     4.  Balance on the gate and get onto the wall (to the right). Now
walk on the top of the wall towards the church and Hammond's house.

     5. Way before you reach anything, you will see a niche in the top
of  the  wall.  Don't  try  to  jump  over  it. Just keep walking. The
computer will suddenly load up the easter egg level.

     The level has: all the weapons, a raptor, two gold bars(?????), a
gray  InGen  card,  a HUGE stone domino set (that you can really knock
over...I felt like National Lampoon's at Stonehenge), each of the four
corners  are marked with a funky floating cube, a large floating paper
airplane-like  thing  pointing  to  a  little path in the land (if you
follow  the  path  you  can safely "fall" off the world onto the white
"nothingness",  where,  I  suppose, you are stranded for all eternity.
Some   vacation.),   a  severed  human  head  (one  of  the  folks  at
DreamWorks?),  and  several  perplexing  "markings" on the ground (one
appears  to have a "beam" of light shining on it from heaven). To make
things  worse,  Annie  keeps saying odd things like, "It looks like it
wandered off the trail" or something like that.