Given the renewed interest in this game of late due to the sequel now having been announced, I am adding this here for anyone new that wants an easy farming guide for unlocking all the Weapon Perk Challenges and getting the Keeper of the Armory achievement. Being that there isn't already one listed here (at least not on Steam that I've found at the time that this is written). In addition, this can also help in completing some Armor Challenges to unlock the cosmetic armors available (there's no achievement for completing them though).

This guide is most useful for those that are unable to find a multiplayer match or otherwise just suck at it and can't compete well enough to complete the challenges.

In order for this guide to successfully help you in achieving your goals here, you will need (at minimum) the following items:

• A working computer.
  
• Internet for the computer.
  
• A Steam account.
  
• A copy of the Warhammer 40000: Space Marines game on the Steam account.
  
• 2 battle-brothers with a copy of Warhammer 40000: Space Marines on Steam and who are willing to just stand around for a while and die for you in the name of the Emperor.
  
• Lots of patience.

To get started, you'll want to:

1. Make sure your computer and internet are still working and that you can sign into Steam.
   
   
2. Make sure you have your battle-brothers on your Steam friends list.
   
   
3. Start the game.
   
   
4. Select the Online option at the Start menu, then select to create a new Versus Private match.
   
   
5. Invite your friends from your Steam list to your newly created lobby.
   
   
6. Figure out your rotation. You want to be fair with who you're playing with. Unless they've already maxed out, you need to give them a chance to work on their challenges also. So you'll need to determine your time limit based on everyone's attention span so they don't get too bored before their turn and just quit on you.
   
   
7. IMPORTANT! Whoever will be getting killed (referred to as the Killee), NEEDs to use the Tactical class while in game and NEEDs to make sure they have the 'Rapid Deployment' Perk equipped for the class for faster deployments/shorter spawn times at the control points.
   
   
8. Whoever is doing the killing (referred to as the Killer), make sure you have your loadout properly customized so you can kill as fast as you can with your weapon of choice you are working on (IE; if you've already unlocked some useful perks, make sure they are equipped), as well as have at least 1 additional loadout ready to switch out to during your turn if you complete your first one early and have multiple other challenges to complete still. This will help maximize everyone's game time.
   
   
9. Ideally, your game settings should be the following for the best results:
   Game Type: Seize Ground
   Map: Waste Management
   Respawn: Instant
   Time Limit: 10 minutes (recommended)
   Score Limit: Unlimited (adjust as preferred)
   Max. Armor: Quarter
   Armor Regeneration: None
   Friendly Fire: On (not necessary, but in case of issues)
   Allow Perks: On
   
   Why these settings?
   Using Seize Ground allows a spawn point that your friends can regularly spawn at allowing you to camp it and immediately kill them instead of having to hunt them down around the map or force them to have to keep running out of their base.
   The Waste Management is a small map that has a good center control point that can be easily reached from both sides.
   The Time and Score Limits are recommendations for fair play to allow everyone involved a chance to play and not get bored, but also enough to complete a number of challenges. I found the 10m/unlimited combo to work best. Feel free to adjust as desired.
   For the Respawn, Max Armor, Armor Regen, and Allow Perks; obviously these settings just makes it easier to get kills.
   
   
10. Be sure the Killer is on their own team and all Killees on the opposite. IE; a 1v2 match. See also General Notes 1 section for bonus armor challenges info.
    
    
11. On game start, the Killees must capture Control Point B. NO ONE should be killed before it is captured. This will allow the Killees an easy spawn point for farming.
    
    
12. Once captured, Killer may start their rampage. However, the Killer MUST NOT capture the control point or it will prevent the Killees from re-spawning and force them to have to run all the way back from their start area.
    
    
13. Killees MUST NOT attempt to kill the Killer unless requested, as this can break their farming, most especially for the Killstreaks, and will more importantly, just waste everyone's time from having to start over again.
    
    
14. Continue the cycle of death until match completion or you finish your challenges. Then rotate the Killer out to Killee for the next person's turn.
    
    
15. Continue this process until everyone has completed their challenges or just gets too bored to keep doing it. Whichever comes first.

1. For Team selection, you may want to keep in mind if anyone cares about the Armor Challenges (there are no achievements for them, but they do unlock cosmetics).
   • For the Killer, when working on the Killstreak weapon challenges for the Bolters weapons (Standard/Storm/Twin/Heavy), there is both a Space Marine (Relic Power Armor) and Chaos Marine (Armor of Rage) Armor Challenge that can be unlocked. These armors can be easily unlocked when doing these weapon challenges as only 50 kills are needed for each side to fully unlock the armors. It is 100 each (or 200 total) if you want the full completion of the challenges on both sides, regardless of armor.
     
     
   • For the Killees, as they are destined to win the match due to the farming setup, it is ideal for them to be on the team that will help them unlock the Armor challenges for Wins. 50 wins are needed for the full Space Marine armor (Mk8 'Errant' Power) and 100 for Chaos (Black Crusader). It is 150 each (or 300 total) if you want the full completion of the challenges on both sides, regardless of armor.
   
   
2. 3 people are only needed if you're working on the Multi-Kills challenges for the Plasma Cannon, Melta Gun or Vengeance Launcher. Although, having an additional person available will still help speed up farming everything else. Otherwise, you can still make do with just 2 for a 1v1.
   
   
3. When working on the Extreme Range challenge for the Lascannon, this is still doable on the selected Waste Management map. The Killees need to stand back against the wall for the spawn point in sight of the direction of the Killer's start point. The Killer will need to stand by the back wall by the start point directly in sight of the center spawn point pathway.
   
   
4. When working on Killstreak challenges for the Bolters (Standard/Storm/Twin/Heavy), keep in mind that the kill streaks are only recorded on the 3rd kill (regardless of what appears on screen). With this in mind, after every 3rd kill, switch to a different weapon and get a single kill with that weapon, then switch back to your killstreak weapon and get 3 more kills, then switch again and repeat. Continuing to just get consecutive kills without switching will NOT complete the challenge.
   Example: Using the Bolter, get 3 kills to earn 1 Killstreak. Then switch to the Bolt Pistol and get a single kill. Switch back to the Bolter and get 3 more kills to earn another Killstreak, then switch back to the Pistol again. This also helps to work on the Pistol challenges as it is a kills only challenge and you don't need to work/focus on it in a separate session.
   
   
5. Some unlocks do require level increases, such as for most of the weapons and additional loadout slots. While the killer can gain a good amount of XP from this, I personally recommend having the group play through the Exterminatus mode first as you can gain level ups there and also have everyone be able to play instead of just waiting around dying. All weapons should be unlocked by level 22. Plus, Exterminatus is just fun to play in general and has it's own achievements to unlock if you can manage to finish it.
   
   
6. It should also be noted that as you are repeatedly killing the same person multiple times over without being killed yourself, this can also earn you Grudge Kills which works towards unlocking the 'Armor of Hate' Armor Challenge. The more Killees available during a match, the faster this will earn as you can only earn 1 Grudge Kill per person per match.

While doing Keeper Achievement and Weapon Perk challenges, it is also possible to unlock/earn all or part of the following:

Armor Challenges:

• Armor of Hate - For the Killer only. Much easier if more Killees are available. As explained in General Notes 6.
  
  
• Armor of Rage - For Killer while on the Space Marine team. As explained in General Notes 1a.
  
  
• Armor of Scorn - Workable for both sides if the Killee is allowed to get a couple kills.
  
  
• Battle-Damaged Power Armor - Mostly for the Killee, but possible for Killer too, but requires Killees to get some kills.
  
  
• Black Crusader Armor - For Killee while on the Chaos team. As explained in General Notes 1b.
  
  
• Blood Disciples Armor - For Killer while they are using melee weapons. Should come naturally.
  
  
• Daemon Armor - Mostly for Killer as Killees will not earn much XP.
  
  
• Master-Crafted Power Armor - For Killer while they are on the Space Marine team for just general kills.
  
  
• Mk4 'Maximus' Power Armor - Mostly for Killer as Killees will not earn much XP.
  
  
• Mk6 'Corvis' Power Armor - Possible, but requires a lot of team work and could very much extend out the play time. Primarily for Killees, but if friendly fire is turned on, it may work for both.
  
  
• Mk8 'Errant' Power Armor - For Killees while on the Space Marine team. As explained described in General Notes 1b.
  
  
• Raptor Shock Armor - For Killer while they are on the Chaos team for just general kills.
  
  
• Relic Power Armor - For Killer while on the Space Marine team. As explained in General Notes 1a.
  
  
• Veteran's Power Armor - For Killee if playing at least 1v2 and allowing Killees to get a couple kills.

Achievements:

• Armored in Glory - Easily doable if also working on the Armor Challenges.
  
  
• Battle Brother - From just earning XP while playing and getting level 10.
  
  
• Captain - From just earning XP while playing and getting level 30.
  
  
• Chapter Master - From just earning XP while playing and getting level 40.
  
  
• Defender - Possible on both sides, but will require teamwork which may extend out the playtime.
  
  
• Devastation! - Easy for the Killer if you switch over to an Annihilation game for a single match, but requires spending time hunting down the Killees due to random spawning.
  
  
• Down to Earth - For the Killer, but requires a bit of teamwork which will extend play time.
  
  
• Jack of All Trades - Should come naturally while as the Killer.
  
  
• Master of Armors - Will come naturally while as the Killer.
  
  
• Master Crafted - Possible if working on Armor Challenges, assuming you haven't already completed the Single Player campaign.
  
  
• Shapeshifter - As long as you switch your class during a single match. Easier for the Killee than Killer.
  
  
• True Son of the Emperor - For the Killer from just general killing.
  
  
• Veteran - From just earning XP while playing and getting level 20.
  
  
• Warrior of Darkness and Light - Doable as long as you're switching teams between each match.

Thank you for reading and hope this was some help to someone.
This was and still is a fun game for any Warhammer 40k fan despite it's age.
I look forward to seeing what comes of the sequel!
https://www.focus-entmt.com/en/games/warhammer-40000-space-marine-2

For the Emperor!