Warmachine is a fantasy-slash-steampunk wargame produced by Privateer Press. It is based in the Iron Kingdoms, which was originally a setting for 3rd edition D&D, and has now been republished with an original RPG system based on the Warmachine rules. Meta.
Hordes is another wargame with the same combat system, set in the Iron Kingdoms, which has fundamentally similar rules, except that Hordes has a lot less steampunk and a lot more giant roaring monsters. Since Warmachine armies can do battle with Hordes armies with very few ill effects (at worst, you'll have a couple of spells or abilities that won't affect the enemy army), and the vast majority of tournaments allow either Warmachine or Hordes armies, the titles of two games are often portmanteau'd into "Warmahordes".
Warmachine follows a better update schedule than the Warhammers, and every army gets about five models per year. This also leads to Warmachine being very well-balanced game, although there are certainly quite a few over/underpowered models to be found if you shop around for them.
Also commonly known as Skubmachine.
Warmachine uses 2d6 rolls as its core mechanic, which produces a rough approximation of a bell curve. Many effects allow you to add an additional die to a roll, or allow you to roll an extra die and drop the highest/lowest. A few effects also force you to roll one less die.
The game has a pretty heavy melee focus, with most ranged attacks having piss-poor range; if you shoot someone and they don't die, they're fairly likely to turn around and charge you next turn. This is not to say that ranged attacks are always bad, because some ranged models hit like a truck; it's just that an army made up almost entirely of ranged models is going to have a bad time.
When trying to kill something, attack rolls are made with by rolling 2D6 plus attacking model's melee attack stat (MAT) or ranged attack stat (RAT) if they're using a ranged attack, against the target's DEF stat. If the attacking model rolls over the target's DEF, then they roll 2D6 plus the POW of their weapon, and if it's higher than the the target's armor, a damage box in the target is filled. Infantry usually only have one paltry box, but warjacks can go up to 36, and don't even ask me to count what colossals get.
 What's what on the battlefield
Armies in Warmachine center around a warcaster, a battle-wizard that controls the army's steam-powered magic robots, called warjacks, in addition to using spells that aid your army or screw over the enemy. At the start of each turn, a warcaster automatically generates between 5-10 focus, which it can keep to use for spells, or can allocate to warjacks (as a general rule, close-combat monsters get 5-6 focus, while spell-slinging squishies get 7-10, with 6-7 as an average).
Focus can be used to generate additional attacks or add an additional D6 to attack or damage rolls for either a warcaster or a warjack (though warjacks can only have three focus allocated to them a turn), and unspent focus gets added to a caster's armor value. While you generally want to use it on other stuff, "focus camping" can be a powerful (and annoying) strategy in the right hands: the Harbinger of Menoth, for instance, has terrible defensive stats and an easy-to-spot large base, but also has ten focus. Saving a little at the end of the turn can help her shrug off weak ranged attacks that would otherwise chip away at her fragile body. Unused focus doesn't carry over to the next turn, so it's important to try and find some use for it, which is why learning to only give your 'jacks focus they can spend is such an important part of the game.
Once per game, a warcaster can use a feat, a unique ability that have a huge effect on the battle, certain feats having more effect than others, and some being fairly hard to pull off. Since they're one-use, make sure you know what you're doing when using them.
Under the default rules, if your warcaster dies, you lose regardless of the current situation, so many games revolve around trying to kill your opponent's warcaster.
Warjacks, the machines controlled by warcasters, are usually the most powerful individual models in the army. They tend to be easy to hit, but their stats and damage grits mean that they it takes very high powered attacks to do anything to them and that they can take plenty of hits before they get wrecked. In combat, they generally also have the highest-power weapons, and can make power attacks like throws, bodyslams, head- and arm-locks and tramples, all of which are automatically hilarious. They also have "systems" that can be crippled as damage accumulates, reducing their effectiveness, and leave behind cover-generating "wreck markers" the size of their bases when they stop working.
Colossals are like Warjacks with more FUCKHUEG, because Privateer Press wanted to charge $100 per model for something, and the only way to do that was to make it really big. Roughly equivalent to Titans in 40K, but can be fielded at any point level. Colossals are surprisingly well-balanced, since they have about the same defensive stats as a heavy warjack but loads more health and tons of dakka. That said, if you're up against a Colossal and your army is mostly anti-infantry, you're screwed.
After warjacks and warcasters, the main models you use are units. They represent the main infantry of your army. They aren't as powerful individually as warjacks, but they are far more numerous. Units play any number of roles, from being aimed at killing other units, to using magic to support your army, repairing warjacks, or killing your enemy's warjacks. Some units can have extra points spent to add an unit attachment to enhance their performance with new special rules, or a weapon attachment to aid in killing things.
Finally, there are things called Solos, which are like units, but with only one model. Most of them tend to have either lots of special abilities to support the rest of your army or debuff the enemy, or absolutely rapetastic killing power and stat lines. Almost all of them have either eight or five boxes, meaning that, while they can certainly survive the sorts of attacks that would kill the average trooper, anything high-power enough to dent a warjack is probably going to kill them if it hits anyway.
Also note that most every type of model has a variant that's a "character" type model with an individual name, except for warcasters who already characters. This means that only of it can fielded per army. These tend to be better than non-character models (character warjacks are typically souped-up versions of a normal warjack), but they cost more.
Outside of these, there's type of model with its own deployment rules called a battle engine that has only recently been introduced to the game (recent years, but before the colossals). These are basically big, durable vehicle-sized models on the same kind of base as a colossal that are easy to hit that are built with a certain task in mind, like support or shooting. They cost about as much as a heavy 'jack, and are generally much more specialized and slightly less durable, but also don't need to draw from a warcaster's focus to do their thing.
How you build your army in this game revolves around your choice of warcaster. Generally, each warcaster has a spell set that focuses on a certain strategy or supporting certain models, so you should build your army in accordance with that. It's possible to completely change the dynamic of an army simply by changing which warcaster runs it.
five six factions, though the latest has only been revealed and no releases yet and Mercenaries who pretend to be a faction.
Cries of "For the Motherland", red banners, gold stars, frigid bitches, and beardy berserkers personify Khador. They're a northern Imperial Russia/Soviet Union style nation bent on imperialist conquest. Khadoran army tends to be smaller than other armies and usually slower, but their infantry and jacks tend to be much tougher and deal, more damage (though their warjacks have low MAT and RAT and often need boosts to hit anything that's not a heavy model). If you think this is ironic since the real life Russia's tactics were more swarm based, it's quite possible (and even favorable) to make a mostly-infantry army composed of conscripts. On the whole they rely more on warrior models than warjacks because their jacks and casters eat up a lot of focus, and they don't have any cheap or light warjacks, just expensive heavy ones. Their small armies and simple play style, which allows them to also do decently well at ranged combat (not as a good as Cygnar, but no slouch), make them the best choice for beginners. Also don't let their model's speed stats fool you, the real slow factions in Warmahordes are Trollbloods and Skorne, Khador actually has a good selection of stuff that boosts speed.
Cygnar is the most advanced human nation, armed with weapons that resemble WWI era tech and a ton of electricity firing toys, and the inventors of the steamjack. They're made out to be a fairly nice place to live if not for the fact they have some bad blood with Khador (it's complicated, read the Iron Kingdoms world guide to get all the details, suffice to say the hungry bear is greedily tearing pieces out of their northern frontier), the Protectorate of Menoth wanting to overthrow their government while being a few miles from their capital, and being the closest to Cryx aiming to exterminate them and everything else on the mainland, or put simply, they'd be a nice place to live if the continent they were on wasn't a horrible place to live. The other factions may not like each other much either (Khador has teamed up with them against Cryx), but Cygnar is basically in the middle of them all.
Their advanced technology is reflected in that they have the best ranged weapons in the game and play less aggressively than most other factions, though they do still have some powerful melee models. Compared to other factions, their warjacks also have better MAT and RAT so while they might sometimes be less durable, they're better at actually hitting stuff. Most of their units have the ability to shoot as well as fight, giving them something a combined arms feel. Most of their models tend have special rules, fitting their technological feel. Their main weakness is that they don't have a cheap and "in your face" warrior unit or tarpit, even if some of their warjacks are designed that way. Like Khador, they're a good choice for beginners. Also note that they have the widest range of mercenaries that will work with them, but more on that later.
As a side note, Captain Maxwell Finn is a fucking beast.
An island nation of pirates that was taken over by a Godzilla sized dragon named Toruk, the father of all dragons (dragons in the Iron Kingdoms are basically gods, and Toruk is the oldest and most powerful one who created the rest of them). Toruk wants to rule the world (or wreck random destruction, it's a little confusing), and aims to use the army he created in Cryx to aid in removing the other dragons, about the only thing that can kill him. Due to his concern about them ganging up on him, he spends his days sitting around doing nothing while claiming everything is going Just As Planned, whether or not that's the truth is unknown. Cryx is an interesting evil army, composed of pirates, undead pirates, ghost warriors, heavily armored liches, and demonic mutant witches. Their army is the fastest, cheapest, and largest on the table, and is for more advanced players, though this varies with how you build your army.
Cryx excels at assassinating enemy casters, debuffing the enemy, and utilizing "dirty" tactics, but is usually never quite as good in a stand-up fight. Many of their models also have abilities that kick in when they kill enemy models, and as per the tradition of an army with undead units, this includes adding models to their ranks. Cryx's jacks are the fastest and hardest to hit, and generally have fine accuracy and hitting power once they get close up, but are also the least durable of all 'jacks and usually can't shoot for shit if they even have ranged weapons, which are pretty rare in the army as a whole. Their other main weakness is pretty standard for something that relies on debuffs, they don't have many buffs themselves, though here it varies much more widely on a caster-by-caster basis.
 Protectorate of Menoth
A bunch of religious fanatics that worship Menoth, the god of civilization. The church of Menoth began falling out with Cygnar about a thousand years ago since a more benign god named Morrow began gaining favor in Cygnar on account of Menoth being an asshole. While the two churches were able to coexist for hundreds of years, relations between them eventually turned sour, especially due to the then-king of Cygnar favoring Morrow. As a result, the Menite church seceded from Cygnar, wandered off into the desert, discovered petroleum, and endured even more oppression from the previous king of Cygnar, Vinter Raelthorne IV, before his own people voted him out of office in a military coup. The chaos and mismanagement allowed the theocracy to create its own army, the Protectorate of Menoth, to forcibly convert Cygnar (and anyone else who got in their way) back to the "True Faith." While they are certainly not completely evil, and while many genuinely decent individuals are present in both their lore and their army, the Protectorate as a whole are still quite a mean bunch. The French-Italian nation of Llael that was conquered by Khador right at the start of the metaplot has since ended up finding Khador's iron-fisted rule preferable to the Protectorate's after the Protectorate decided to "liberate" their country by invading and occupying half of it.
Protectorate army is about setting up devastating combos, army synergy, and generally setting things on fire ("We put napalm on everything" can be their motto). For example, their 'jacks, fielded on their own, combine the worst aspects of Khadoran and Cygnaran technology into one mediocre package (being as slow and inaccurate as the former and having the armor and durability of the latter), but bringing along the Choir of Menoth will ensure that mediocre package becomes either bulletproof or murderiffic. They also have some VERY strong warrior solos, and though their ranged stuff is about as accurate as a thrown bottle rocket, it tends to compensate through either volume of fire or potential to set stuff on fire in an AoE. Or both, both is fine. Due to their issues with technology coming from Morrow, their army is far more low-tech and has a ton of Gothic design to it. Many of their units include medieval knights and their warjacks have similar designs to many machines in the Imperium of Man. Their main drawback is, as you might have guessed, they tend to not be so tough with their support units removed. Because of the necessity of careful synergy and combo-building in both making and playing their lists, Menite armies are relatively difficult to learn, though, again, this can vary. (Play Necrons in 40K? You're going to rape face with these guys.)
 Retribution of Scyrah
A bunch of jerkass elves who think that their gods are dying because human magic is draining their life force (whether they're right or not isn't stated), so they want to kill all human mages. Their units are designed very differently to any other army and have more of a sleek anime-esque look. They've got some interesting mechanics, like 'jacks with force fields that lose special abilities when they're crippled, dedicated mage hunting units, and ranged weapons with special effects. Most of their army is either jack-of-all-trades units or units heavily specialized in a certain role. However, they're certainly one of the harder and more expensive factions to play, limiting their player base.
They're also fans of shaved heads and can even grow beards sometimes, making them the manliest elves ever, not that this is a high bar to jump over.
 Convergence of Cyriss
New kids on the block, they are not a true robot faction, they just replace all their organs with machinery and thus retain their souls. They worship a god of science and invention that exists as a planet in the night sky that drives you crazy if you look at it too long using a telescope, they've been around since the Witchfire trilogy so they're pretty deep in the lore, but have gone the opposite of the Sensei in 40k. Their warjacks inherit their controller's MAT and RAT, so a spellslinging warcaster is going to have crappy bodyguards while melee casters will have fairly scary warjacks. Each warcaster also gives a unique trait to all the warjacks in their battlegroup like an arc node or (hopefully) weapon master. So far nothing is released yet, but the preview trailer shows us some gorgeous minis with what seems to be fairly average-to-shit stats, but thats going off screenshots of stat cards without any of the rules or point costings.
Once upon a time Mercenaries were meant only as additions to the real factions, so that two armies of the same faction wouldn't be composed of exactly the same troops. Since then, mercenary fans forced PP to make a number of mercenary "contracts" to allow them to play weaker armies . As of MKII Mercs possess some of the most awesome warcasters, including Magnus the Traitor/Warlord who has the most awesome backstory for a character in the game and some of the most annoying abilities ever. Mercs are awesome because they get paid to get shit done and literally have access to a character for every rule breaking exploit, except for Protectorate Choir of Menoth, no one gets anything that broken. That said Mercs currently have the best tournament meta advantage, as the 2 List format and contract system means that your opponent will have to face one of two armies who are radically different from each other and share no units (other than Eyriss and Gorman di Wulfe, but they're played by every single player who wants to win, and isn't Cryx) or common weaknesses.
There are four mercenary contracts in the game (there used to be five, but one of them got demoted thanks to new rules in MkII):
- Four Star Syndicate; Pick up every mercenary you own and put it on the table. Done. Allows you to play Magnus The Awesome or Epic Magnus The Super Awesome, without having to commit to tier lists (a tier 4 pMagnus list is pretty nifty though). Supposedly represents merc working for a huge mafia/trade consortium making this literally a PMC gone rogue.
- Highborn Covenant; they're French, see above and add some of your own models if you play Cygnar, since their list is composed of every model that will work for Cygnar plus gun mages. A bunch of rebels fighting to restore the nation of Llael. Said nation has been conquered by Khador, then half-counter-conquered by the Protectorate, so their prospects aren't bright. Considered the better contract in events, it has access to 2 Cygnar units that Mercs don't have a version of their own, a warcaster who is a combat monster against infantry and some mercs that are pretty good but not available to Four Star. Also has an army wide ability to redeploy solos after deployment is finished, but before the game, making it instantly better than Four Star.
- Searforge Commission; They're Dwarves and thus the only viable Mercenary contract not including a fellow named Magnus. Note, however, that the Dwarves in this universe are not Scottish, because the Trolls are already Scottish. It is generally agreed that the Dwarves in Warmachine have a New Zealand accent. Also, no beards (the elves stole them), except for the mad 'splosionmancer Durgan Madhammer, who has a short and scruffy neckbeard. Plays like no other faction due to Dwarfs being slow bricks while everything in this game is about aggression, that said 2 of its warcasters are pretty hard to kill and the third, Gorten Grundback is one of 2 warcasters in the game that are harder to kill than the army they lead, not mention he has a notorious buff which allows him to make one of his jacks have enough pow+strength to instagib light warjacks or one hand throw warjacks three times its weight back to their controller for the steampunk version of hitting someone with their own fists; never play assassination against Searforge, you will just solve their mobility issues.
- Talion Charter; A bunch of pirates. Lots of pirates. How many pirates can you imagine? There are more than that. Also, a peg-legged Napoleon dwarf. Also, a fuckhuge cannon that is easily the best damn artillery piece in the entire game if you manage to get anything in its line of sight. This group is all about synergy with their units, which on their own are the worst in the game. But start adding in their solos and unit attachments, suddenly you've got yourself a unit that can do some damage to anything, is annoyingly hard to kill, and can add models to it after killing them.
 Getting into Warmachine
Go to: http://battlecollege.wikispaces.com/ for more information and advice on how to start an army, as well as the official site: http://www.privateerpress.com/WARMACHINE/default.php.
It must be said that it takes far, far fewer dollars worth of Warmachine stuff to enjoy yourself than other games. You'll be paying about the same price per model as you would for Games Workshop stuff, but you will be fielding a lot less models per army, and the game is actually fun (but not hugely balanced) at low points levels.
If you like a faction, don't let the "beginner/expert" bits above scare you. Some factions are generally trickier than others, but none of them don't have builds that even brand new players can find easy to use.