Doom/E2M1: Deimos Anomaly

Mission 1: Deimos Anomaly
One thing that makes this episode so hard to start with is the fact that you lose all your weapons and such from the previous episode, starting with just 50 pistol bullets. Oh well. Start by heading right around the corner (ignore the teleporter for now) and killing the marines. Sprint through the red cross (it hurts you if you stay there) and grab the blue keycard at the end. Turn around and go through the teleporter near the start. Ignore all the enemies here for now and grab the shotgun. Carry on around, killing the shotgun marines you see for ammo and ignoring the rest until you can grab the security vest and box of shells on the platform above the blood-coloured slime. Now you are equipped to clear out all the other marines and Imps. Once they're all dead, hit the switch by the slime, then hit the switch that comes up out of the ground. Turn around and go back through the teleporter you came through. Head back around to where you found the blue keycard, and you'll see a teleporter has appeared here. Go through, fire at one of the Demons to get their attention, then head back through the teleporter and wait on the other side for some of the enemies to come through. You will find a Cacodemon in here, which is the toughest normal enemy you've faced yet. Once it's relatively safe, head back through and clear the place out. You'll find a cell in here, as well as a shiny new Plasma Rifle!

Retrace your steps to where you were before. Check the back of the switch that came up out of the ground for another switch which opens an area by the teleporter which contains a medikit and a red keycard. Go through the teleporter, and snipe the Demons from down here before you trigger the wall to lower and let them down. The skull switch next to the switch that lowers the wall will open a secret room which leads to a long corridor containing a large number of armour and health bonuses. Past the wall that lowered, you'll find the red keycard door up ahead. Quickly run down onto the blood-coloured slime to open it, then back AWAY from the door and shoot the shotgun marines and Spectre on the other side (don't run straight through as you'll get trapped on the slime at point blank with them, and most likely die). Once they're all dead, head through for a medikit, Computer Map and combat armour.

Turn around and go around the corner to find the blue door. Go through and use the teleporter. Kill the Demon and Imps on the other side, then head over to the far side of the room to find a switch. You can use this to raise a staircase up to a switch, unfortunately right next to it is another Cacodemon. Once it's dead, head up and throw the switch to lower a wall revealing another teleporter. Head on through. The room at the other end appears to be a dead end, but if you approach the far wall it will lower, revealing the exit door behind another Cacodemon. You may be running low on bullets and shotgun shells by this point, so blow it away with 20 rounds from your Plasma Rifle. Head through the door, fry the Imp waiting behind it, and hit the button to leave the level.