DOOM

This trophy is straight forward and you shouldn't need a guide. I will however post the secrets guide I have written for it that shows where every bit of loot is in the level.


From the start of the level you will jump down and then climb up a ledge. There will be a Codex Entry on the ground in front of you:


You will jump down to the next area and fight some enemies. Then head on and find a locked blue door. To the right of this door you will follow the path around to find the blue key. Above the key is a ledge that hold the first collectible (Classicguy):


Once through the blue door, you will jump down and fight a few demons and then the path splits. You should take the right path which leads in to a cave. In here you will find an Automap that reveals the whole map:


Follow the cave to the exit and you will find a Praetor suit upgrade:


Drop down from here and kill all the enemies. Then drop down again and you will be next to a secret door that looks like this:

Clear all the enemies out and then you can locate the switch. If you stand with your back to the door, then you should see writing of "TRI 9C" on a bit of scenery. Underneath this is the switch you need to pull to open the door:


I won't reveal the contents of the secret area as it is a nice surprise. Once you have entered the secret door, come back out and climb up above it and jump over the gap. You should see 2 caves in front of you. Take the left cave first to grab the second codex entry:


Head back to the cave split and take the right cave now. At the entrance will be a gun upgrade:


Fight through the next area and once all enemies are cleared out follow the middle path through an archway and you should reach a dead end with a green shield pick up above you. As you face the shield on the left wall will be a cave entrance:

This leads to another secret area with the second collectible (Blueguy):


Now you just need to work your way to the end of the level through more enemies.