This is getting serious!
This article contains spoilers. It might spoil your gaming experience when first playing these games.
Sam has entered the Sacred Yards, but it has nothing to do with his mission. He only entered them to fight more monsters.
- In the area with 'Pinky' (a very small Common Aludran Reptiloid), shoot a rocket at the pillar/small obelisk in the middle to reveal a secret Large Health.
- When you're in the left area with the sphinx, as you see the platform rising, immediately shoot a rocket at it to blow it up. It will explode, and you'll be able to pick up the sphinx just like that. (NOTE: This secret does not work on the Xbox 360 port of Serious Sam HD. As soon as the rocket touches the platform, the game will crash, and the only solution is to reset your console. There is no way around this bug, so this secret must be skipped).
- After you hit all the switches in the left area with the sphinx, go behind the platform that has the sphinx on it (or had, if you destroyed it), and use the switch. That will rise a platform which will allow you to pick up the secret Super Health and Extra Large Armor.
- (HD-only) In the right area with the sphinx, as you enter, turn left, you'll see an Ammo Pack. Pick it up to register the secret.
- As you're pushed by the wall into an open area with a pyramid, clear all enemies, then look for some Croteam Bigheads coming out from a door. Enter the door and hit the switch to turn the pyramid into a bunch of crates.
- Walk behind the pyramid, to its right is a Super Health.
- Opposite of #6, to the left behind of the pyramid is a Serious Pack.
- Back in the right area with the sphinx, do not hit any switch to make the water level rise. Instead, go to the "middle" platform with the switch, jump on it, and from there jump behind the wall into the sphinx and pick it up. This will not count as a secret if you have raised the water level.
- Still in the right area with the sphinx, go to the left platform, and jump on the button, and then on the ledge on what the button is on, and from there, jump onto the ledge sticking out of the wall to get a Super Armor.
- Opposite #9, there's a Super Health.
- Still in the same area, there's a platform sticking out on the left, near the middle platform. Shoot it with a rocket. This rises a platform in the opposite position of where the blown up one used to be.