I continue to thoroughly enjoy Warhammer 40,000: Gladius - Relics of War, i.e. the best Warhammer video game of all time and one of my favorite 4X games ever. So far, the faction I've liked playing the most has been Chaos, and just before the Eldar DLC dropped, I managed to win as Chaos on Very Hard. This is how I did it.
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First, a few words on the kinds of units you'll need. There are three main roles for Chaos units in the game.
For starters, you need units that can tank damage. To win at Gladius, you need to be able to destroy enemy cities. They, however, will tend to shoot back, and the enemy may also have units of their own. Similarly, when you need to defend your own cities, you want the enemy beating up on your units rather than the city.
Heroes, especially properly outfitted Chaos Lords, eventually become very, very good at this, and even regular Chaos Marines can do some tanking, but all infantry is very vulnerable in the open. That's why the real stars here are vehicles. Chaos Dreadnoughts ("Helbrutes" to some people with no respect for the old ways; I'm damn sure Lorgar didn't call them "Helbrutes"; this is Chaos, not some kind of anarchy where anything goes) can take a serious beating, especially if you have a Warpsmith handy to heal them. If you start in an ore-rich area, you should start building dreadnoughts as soon as possible, and keep at it until you can switch to Land Raiders and/or crabs. A line of dreads, anchored by a Chaos Lord and attended by a Warpsmith, can take a lot of punishment.
Remember that a unit that does nothing except absorb enemy fire or melee attacks is doing a valuable job! In the early game, it's often worth bringing cultists or spawn along to attack enemy cities; every enemy shot fired at them isn't hitting your important units. It feels to me like the AI disproportionately targets spawns, so use that to your advantage.
The second thing your units need to do is, obviously, deal damage. Dreadnoughts suffer from only having the reaper autocannon as their ranged attack, so a little fire support never goes awry. Havocs are amazing for this: with a range of 3, they can sit behind your characters or dreadnoughts and blast away. Remember that they're very vulnerable, though, and never leave them in the open if you can help it.
The stars of damage-dealing are undoubtedly Chaos Lords, especially once you get Exalted Strike. They can't win wars on their own, though, and can get swamped by even weak enemy units and worn down, so they need strong support. I haven't really found Berzerkers worthwhile, even though I love them in the tabletop game; they don't really do enough damage and are quite vulnerable to enemy fire. The same goes for Warp Talons, and both they and Berzerkers suffer from competing for the same resources and build slots as Havocs, and usually I'd rather have the Havocs. Obliterators are very strong, but surprisingly vulnerable in open terrain.
Similarly, I'm not that impressed with Maulerfiends, whose special ability against fortifications is a bit niche, or Venomcrawlers, because again, they compete with dreads, and later with Land Raiders and Defilers. So I keep ending up with Dreadnoughts and Havocs.
The third area Chaos needs is flyers. The AI likes building flyers, and for good reason: they tend to be shooty, tough, and obviously they ignore terrain, making it easy to concentrate their fire wherever it's needed. I expect anyone who's played on bigger maps and/or higher difficulty levels will have encountered the Ork Dakkajet swarms, and suffered at their hands.
Chaos has no dedicated anti-aircraft units, and is more reliant on melee than most other armies, so enemy flyers, especially in large numbers, are a serious problem. Another strike against Maulerfiends is that they're helpless against enemy aircraft! Leveled Havocs can drop individual flyers out of the sky, but a strong enemy ground force with good air support is the toughest opposition you will face as a Chaos player, and if you're not prepared for it, you're very likely to lose.
The only real answer is Heldrakes, so researching them becomes a priority, especially on Medium and bigger maps. Heldrakes are tough, but can be vulnerable at lower levels; ideally, you should try to get them leveled up by having them participate in fighting in a limited way, but both when doing this and defending against enemy flyers, take care that they don't get cut off from the rest of your forces and surrounded, because they will be destroyed if mishandled.
Heldrakes also require a lot of energy to build and maintain, so that's also something to invest in in the early game, if possible.
The army I won with on very hard was Dreadnoughts, a Chaos Lord, Warpsmith and Master of Possessions, backed up with some Havocs, a swarm of Heldrakes and as many Land Raiders and Obliterators as I could get. The real stars were the Dreadnoughts and Warpsmith, but the Heldrakes also start getting quite scary as they level up.
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So how do you build this army? In the game I won on very hard, I only had two cities on a Small map. Chaos can potentially expand very quickly, but you don't need to. My thinking tends to be that cities either provide access to a resource I need or form a strongpoint for defense. If my starting location is lacking a resource, it's usually worthwhile to found a city somewhere where that resource can be found - assuming you can defend it. My priorities on city placement are access to bonuses from special resource tiles, and approaches and lines of fire. When claiming tiles for a city, it's worth thinking about whether you can create good firing positions for Havocs where they'll be protected from enemy attacks. Infantry really struggle to defend in open ground, but a city can turn a barren wasteland into a very strong defensive position.
My priority has been to get a Chaos Lord in play as soon as possible, so I tend to research Lord's Quarters first. I go for Bloated next, especially since I usually do the first few quest stages; the Imperial Guard invasion is easy experience, and the resource rewards are handy. It's also worthwhile to get Rite of Change anyway for when your cities hit population limits. Up to and including very hard, I haven't really found it necessary to optimize research, so it's mostly contingent on what I have or need. If we have a lot of food, Havocs are a priority; a lot of ore, Dreadnoughts. If you're going to expand, then you need the Meadow of Sorrow sooner rather than later. Whatever you do, you should make fairly steady progress toward the Heldrake because you're going to need them.
After the Lord, you can build a Master of Possessions if you have the influence to spare, but a Warpsmith is more important. In the early game, the Master's ability to heal your units and summon disposable daemon units is useful, but the Warpsmith is crucial to keeping your vehicles - especially Fire Frenzying dreads - alive. His economy boost is also nice, and the mechatendril attack is actually quite good! The Master of Possession's other abilities are a bit lackluster in my opinion.
Thankfully, none of this engine-building requires any micromanagement: just keep an eye on your economy, especially energy, and your cities' population limits and loyalty, and you'll be fine.
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Finally, a couple of words on tactics. I have three principles: terrain matters, overwatch is your friend, and don't overextend yourself.
One of the things that makes Gladius such a good wargame is that you have to be very aware of the terrain and the ways different armies use it. As a Chaos player, close terrain and narrow places are to your advantage - but remember that they'll also slow you down if you need to retreat. Watch your flanks for enemy skimmers and flyers: they can easily cut you off.
Conversely, be very cautious in open terrain, especially with infantry. Lines of sight in Gladius are rather short, so in the open, the enemy can easily surprise you with a flanking move. It's often worthwhile to use a disposable unit like Chaos Spawns as a flank guard for some advance warning.
This leads up to the second principle: overwatch. In a game with strong overwatch and weak or nonexistent artillery, you usually want the enemy to come to you. If they've had to eat up overwatch fire from your Havocs and Dreadnoughts, they'll be that much easier to wipe out in close combat on your turn - if they even make it that far. In the best-case scenario, the advancing enemy is depleted by your overwatch and stuck in the open, exposed to another round of fire. Overwatch is strong enough that even on the offense, it can often be a good idea to make a tactical retreat to lure the enemy into following you.
Finally, maybe the most important tactical principle is not getting overextended. On the smallest tactical scale, this just means not putting units in harm's way to finish off a damaged enemy, for instance; before you know it, an unexpected enemy attack wipes them out. The same principle applies on a larger scale, for example when attacking enemy cities. The AI will often just ignore attacks on individual units, like those random Malanthropes the Tyranids have just roaming around, but will usually make an effort to defend cities. Especially on larger maps, when you start damaging an enemy city, they may have most of their forces fighting elsewhere, but will detach some or all of them to defend the city. So as you're laying your siege, a strong enemy force may well be on its way to relieve the city.
This means that your dispositions should be such that if enemy reinforcements do show up, they can't get the drop on your Havocs, for instance; especially since you'll probably be busy reducing the city, so no-one will have any overwatch attacks. But it also means having some notion of how you're going to retreat if your casualties are starting to look too high. It's better to preserve your army, reinforce it and come back later, than to throw it all away pressing a failed assault. Sadly, Fire Frenzy sometimes means having to leave a dread behind; at least you can hope it'll slow the other guys down.
Even destroying an enemy city has its risks: whereas just a moment ago, your assault force was safely inside a city, it just blew up and left your guys standing around in the open. Tyranid cities are especially nasty, because you're liable to find yourself standing on naked bedrock! It's often a good idea to pull back and consolidate your forces when you destroy an enemy city: if your units are spread out and damaged, they'll be easy prey for an enemy counter-attack - or even a totally different faction suddenly swooping in. Destroying a city sets your opponent back and gets your units experience; sometimes it's best to leave it at that and pick your spot for the next attack.
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That's how I've gotten along so far; next, it's time to up the difficulty some more and see what happens. I also got the Eldar and Tau DLCs, and I would definitely recommend both. The Eldar story is a bit bland and the quests aren't all that interesting, but they're a fun faction to play; I'm currently figuring out how they work on Hard. The Eldar DLC adds webway gates to the map, and the Eldar can only found cities on those. Unfortunately, enemy factions will tend to destroy all the ones they can find - or other Eldar factions will grab them - meaning that especially on smaller maps, you'll be stuck with few cities. I'm kinda interested in finding out how that works out on bigger maps and higher difficulty levels. In general, though, I'm thrilled to be playing my favorite army from Space Marine.
The Tau are surprisingly similar to the Eldar: massive firepower, very little staying power. Their quest is excellent, though, and although the entire army is an innovation, the anime battlesuits are kinda growing on me. It's also just nice to have more variety in your enemies!
Gladius remains an excellent, sadly underappreciated game, and I hope they come out with more DLCs. Compared to Dawn of War, we're still missing the Dark Eldar and Sisters of Battle, but I'm actually hoping to see the Machine Cult show up. Now that we have Wraithknights, how about some Imperial Knights?
Anyway, I've just tried the Eldar on very hard and it went surprisingly well; time for another game...
