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2010.11.19 Minecraft Mob Traps

posted Nov 19, 2010, 6:06 AM by Troy Cheek   [ updated Nov 25, 2010, 5:54 AM ]
A month or two back, I might have talked about Mining and Crafting with Minecraft. As I said back then, Minecraft is an addictive little game where you mine out minerals, craft items from them, use those items to mine/fashion better items, and keep going until a zombie eats your brains.

Zombies are eating my brains fairly regularly these days.  Skeleton archers are shooting arrows at me.  Spiders are biting me.  Creepers are, um, creeping, I guess.  Recent updates have added an alternate dimension called the Nether.  In this world, game physics are altered.  New creatures are revealed.  Zombie pigmen squeal and ghasts shriek.  I have new ways to die.

Another thing recent updates have done is tweak the mobs.  "Mobs" is just a fancy name for the creatures of the world.  Given the blocky, 8-bit appearance of the Minecraft game world, I thought "mob" was a reference to the old name for a game sprite, the Movable Object Block.  Back in those days, most of the game screen was a set backdrop with just a few things moving on it.  Those moving objects were called mobs.  However, it's since come to my attention that various gamers have been using mob to refer to mobile game characters for years, even in games that don't technically have graphics.  Oh, well.

Anyway, the mobs are a bit smarter now.  They are slightly less likely to jump to their deaths trying to reach you.  Though the pathfinding is minimal, they at least recognize cliffs when they're about to walk off one.  They are also much better at swimming.  That's a problem for me.

While it was probably not intended by Minecraft's creator, mob farming has been a staple of gameplay for a while.  Since mobs are pretty dumb and predictable, it's possible to design a structure which they can enter but never leave.  You can construct traps which will attract and kill mobs with little/no user interaction.  This gives you all the benefits of killing monsters with little of the risk of facing them in open combat.  (The benefits are that sometimes mobs drop useful items when they die and that if a mob is stuck in your trap, he's not outside running around trying to kill you.)

Some people see mob farming as cheating.  They see it as rewards without risk.  However, I personally believe that anyone who thinks mob traps are cheats has not gone to the effort of designing and building one.  Hundreds of man-hours have gone into designing mob traps.  Even if you're using someone else's design, you still have to customize it to fit your particular situation.  You have to fight off mobs while you're building.  It's not unusual to be nearly finished with a finicky design, finally having everything just right, and having it all blown to pieces by a wandering creeper.

Furthermore, there's a bit of an arms race between Minecraft's designers and Minecraft's players.  The short version is that as soon as the designers introduce something new, the players come up with a way of using it in a way that the designers never thought possible.  The designers tweak the design so the players can't do that anymore.  Another player comes along and takes advantage of the new behavior.  More tweaks.  More traps.

Since mobs take damage from falling and don't always pay attention to where they're going, a primitive trap would be to dig a deep hole and stand at the bottom.  Mobs would rush to attack, fall to their deaths, and leave their drops where you could pick them up.  Mobs haven't been quite that stupid in several revisions, so traps have gotten more sophisticated.  Mostly, this involves using water currents to push mobs into pits, fire, cactus, or other things that cause damage.  My first trap involved mobs brushing up against lava, but I'd heard a lot about drowning traps.

Drowning traps work because in Minecraft even the undead (zombies, skeletons) and undetermined (creepers) need to breathe.  In the past, it was fairly easy to trick a mob into drowning.  However, about the time I decided to try building a drowning trap was about the time that mobs learned to swim a whole lot better (v1.2.2 or so).  In fact, some of these guys look like they're beach balls bouncing around on top of the water.  Mostly, they're bouncing around on top of the water in my drowning trap.  This was very annoying.  I tried to make the downward currents stronger, make the drop deeper, make the holes wider, but I still had skeletons dancing around on top of my trap shooting arrows at me while I tried making adjustments.  I gave up and went back to lava.  Sure, it was a pain to go all the way down to the bottom of the earth to collect it, and I kept burning myself and all my possessions, and it would incinerate half the good stuff that the mobs would drop when they died, but at least skeletons weren't dancing on top of it.

Mob Elevator

(Naturally, others tell me their drowning traps are still working perfectly and that I'm just doing something wrong, but I know better.  Minecraft is out to get me.  You hear that, Minecraft?  I'm on to you!)

Anyway, I wasn't the only one who noticed that mobs were floating around like party balloons.  TyrannosaurusHax noticed and used this new behavior to create a mob elevator.  In spite of all the people telling me that mobs still can't swim all that well and still sink to the bottom of the pool eventually, T-Hax demonstrates that these things have more buoyancy than Pamela Anderson.  His mob elevator (or mobavator) takes mobs from below and pops them out top, easy as you please.  It made me wonder why my mobs were still having to take the stairs.

I immediately went out to replicate his results.  I immediately failed.

My plan was to make a mob elevator so high that when the mobs fell off the top, they'd go splat.  Yes, I was going back to the fall trap of Minecraft's ancient past (a few months ago when I first started playing).  However, I discovered something interesting.  Most of my mobs weren't making it to the top.  As I built higher and higher, fewer and fewer made it to the top.  They were dying somewhere along the way, based on the items dropping to the bottom.  I tried to swim up the elevator myself and discovered the problem.  The mobs were drowning during the long swim up.  I started redesigning to create air pockets and way stations, but then it hit me:  I had been trying to drown the darn things before.  Why was I trying to save them now?

I was experimenting with how short I could make the trap and still drown all the mobs when I managed to get trapped under a poorly placed piece of cobblestone.  Experimentation showed that mobs got trapped under the same stone.  The mobs, with their new magical swimming ability that rivaled some famous swimming person, could swim up just fine, but couldn't figure out that they needed to swim down to keep from drowning.  Depending on the mob, you could drown them in a single block of water over a ladder.

Yes, I could drown skeletons with the equivalent of a bucket of water over a door.


Ahem.  Sorry.  I got carried away there for a a second.

Skelespawner Float Trap 2000

Anyway, after entirely too much time building and rebuilding, I finally came up with the Skelespawner Float Trap 2000 as described in this Minecraft forum post.  Skeletons go in.  They don't come out.  The only thing that comes out is a steady stream of arrows.  I use the arrows to shoot at other skeletons.

I hope the video came out okay.  It's my first Minecraft video and only my second YouTube video at all.  I had pretty much forgot that I even had a YouTube account.  I created it when I was planning a machinima series a few years back.  That never went anywhere.  At this point I don't plan to do a Minecraft video series, but I am happy how this one turned out.  The YouTube user tools, especially the annotations, have gotten a lot better than I remember.

Anyway, back to watching skeletons drown!

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