This Serious Sam 4 Guide and Walkthrough will help you through the mission Death from Above with all side missions.
Find Father Mikhail
Watch the cutscene where you are being introduced into the mission, also if you noticed, a crash happens. After waking up from the crash, you will get to know your new buddy Kenny. After this cutscene ends, the level begins.
Cutscene is over, great. After automatically equipping your weapon you should go near the checkpoint and 3 enemies will spawn. Kill them and Kenny will say a few words about his broken gun.
Follow the tunnel in which you will encounter one enemy. Follow further and another enemy attacks you. Now you have to exit the tunnel and walk straight where you will encounter new enemies which are called “Processed”. Kill them and a few other enemies and walk straight, and you will eventually get a new weapon, the shotgun.
The shotgun is a very classic weapon from the older Serious Sam games, so yes, it’s also in this game. Continue the path and you will get more enemies. Try your new weapon against them. After killing them you will encounter your first female Gnaar.
Continue and more enemies will spawn, also a new one which act like the Boomer from Left 4 Dead.
Over The Wall
After following the path some more, you will get your first choice in the game. Start the side-mission or continue with the main story. I advise you to do the side-mission because you should get to know everything from the game you’ve paid for, right? So go to Kenny and press the button to “climb him” or just jump on the rocks.
Continue the path and you will encounter some enemies. After you have dealt with them, you should go into the tunnel where you have to fight some more enemies. After reaching the end of the tunnel, kill some more enemies and go up the stairs where you can listen to a radio and finish the side mission by collection a Holodecoy from the box.
To get back to Kenny, go back all the way you came from. After reaching Kenny, go to the right into this huge area where you will find your next nice gun. The double barreled shotgun. After picking it up some enemies will spawn. After dealing with them, you should go to the entrance of the building where you will be introduced to a new character, Dr. Kiesel. Be careful, because now a huge monster will spawn right next to you, and he wants to puke at you, so you better kill it quickly. Also, you have to take care of all the other enemies too of course. Now you will encounter a new enemy, the Werebull.
After watching the nice intro of the enemy, the game wants you to kill three of them. They can be easily killed with one shot if you aim directly at their head with your double barreled shotgun. After dealing with them, the gate opens. Follow the street where you have to kill some more enemies and then go to the only option you have, to the left. A huge building gets blown up, and you have to kill some more enemies, great. After that another new enemy get shown to you, the Scrapjack.
Kill it and all the small ones and a huge gate will open. Now a cutscene plays where you will meet another character, Father Mikhail. The level ends here.