Relic and Dawn of War are good examples of how much variation a game genre such as real-time strategy (or RTS) can provide. The same studio has now produced three games with the same dark futuristic setting of Warhammer 40K, and none of them is quite like the others.
It ain't easy being a grunt in the 40K world. Life expectancy is measured in minutes or seconds the moment you're churned out of your respective production centre, and hazards are numerous. In Dawn of War 3, the battleground is set on the remote world of Cyprus Ultima, where three factions are fighting for control. Skirmishes are soon replaced with something far greater and sinister, though, as the lost planet Acheron suddenly appears with all its secrets ready for plunder.
The campaign, which lasts around 15 hours, constantly switches between the three factions, so this means you've always got an up-to-date understanding of the same grand campaign from all perspectives. This also means that it's a bit more challenging, as you only get to play a single mission with one army at a time before getting swept away to control something quite different. Blood Ravens, lead by the illustrious and grumpy Gabriel Angelos, are the most straightforward army of the lot. Space Marines can take a beating, dish it back in spades, and use conventional weapons and special abilities such as grenades or rocket barrages. They're definitely the easiest to get to grips with, and so will probably be the favourite of many a player, at least in the beginning.
Orks are lead by the war boss Gorgutz, and his lot resemble the Space Marines at times, but with weapon and skill designs conjured up by a mad scientist instead of a team of weapon specialists in a lab. Ork weapons deal huge damage, but are erratic and constantly either falling apart or exploding. The faction's special trait is the scavenging and looting of scrap, and scrap is either generated periodically by their towers or from destroyed vehicles and buildings. When collected by a squad or vehicle, scrap boosts their stats and unlocks their unique ability. Scrap can also be scavenged to create a new Ork unit out of it, and the bigger the scrap, the bigger the unit. To fully exploit the trait, the player must be ready to micromanage the troops a bit more, but can, in turn, rebuild much faster after a big group fight.
The third party involved are the Eldar, with Warseer Macha as their leader. Eldar are the most vulnerable of the bunch, but can offset this with their regenerative shields and pure speed. The shields (called Battle Focus in the game) can withstand a bit of a beating, after which the rest of the damage goes straight to health. These two traits make Eldar the optimal hit-and-run army, especially with their hover tanks and bikes. During the campaign and especially in the multiplayer, they require the most micromanagement, since they can't hold the line the way Space Marines or Orks can.
Dawn of War 3 plays a bit like an amalgamation of the previous two iterations. It's got the streamlined base-building from the original, with half-a-dozen structures per side to build and very little incentive to go for multiple barracks, for example. The slow intake of requisition and power points from the captured resource nodes is usually the limiting factor when building an army, not the speed in which the units are manufactured. From Dawn of War 2, this game takes the customisable hero units and slightly downgrades them into less fleshed-out elite units, some of which have a whole backstory (like factions leaders) while others are "just" very powerful versions of existing troops like Dreadnoughts.
Elites can be called into the fray after accumulating enough elite points, and vary wildly in terms of their skillsets. Cheap early game units like Ork Kommandos are excellent in capturing requisition points right from the start, while mid-tier assets can start pushing the frontline. Late-game mega units are bigger than ever with Gorkanaut, Eldar Wraithlord and Imperial Knights towering over the other, already impressive elites. They're not invulnerable though, so calling one in is unlikely to turn the tide of war in your favour if the enemy is already knocking down your base. They can, however, provide an edge to break the gridlock in an evenly-matched contest.