Serious Sam Easter Egg - Big Heads

I can't take credit for this. I read about it somewhere.

When you start the game, do a 180 and head down the stairs. At the bottom platform, go to the front left side of the building. Find the door and watch it open. You'll see the programmers run out with huge heads. Each one will come to you and announce a specific name.

This is how Croteam thanks those who supported them.