In most cases, by the release of an "addon", developers mean adding a side of the conflict, several new maps and a fresh storyline that fits into a paragraph of text.
Warhammer 40 LLC: Dawn of War - Winter Assault was made according to a similar scheme, the more pleasant were the surprises presented by Relic in the Dark Crusade. In addition to the five available, two more races "tau" and "necrons" ( necrons). Resting in their tombs for the time being, the "necron" death machines are good for relatively slow development, and as a result, they increase their power to unprecedented heights. Add to this free fighters, the ability of the main character to resurrect those killed in battle, a flying fortress, which the citadel turns into, and it becomes clear why this race had so many fans before the first fixes. In turn, under the banner of "tau", troops gathered, adhering to the tactics of "hit'n'run", preferring not to give the enemy the opportunity to even approach. We have at our disposal not only powerful artillery, but also armies of "drones", and heavy fighting dinosaurs, and a hero literally stuffed with small arms. Most of all "tau" resemble "eldar", although still more human, may the adepts of the Warhammer 40K universe forgive me.
They did not remain without gifts, and the five races we have already seen - each added a strong unique squad that compensates for the weakest sides of their tactics. However, now the number of super-powerful units simultaneously present on the battlefield is limited, so it will no longer be possible to fight only with terminators.
Unlike past campaigns, in Dark Crusade, an entire planet will be the battleground. The surface of Kronus is divided into 25 territories, for which you will have to fight to the bitter end. Turn-based battles on the global map are complemented by pleasant surprises in the form of bonuses from individual captured provinces (for example, the ability to attack twice per turn, or even move almost all over the map). As we successfully capture the planet, veteran units will join us, making it easier to start in new territories. And the chosen hero can be hung with additional equipment that increases the characteristics - a worthy reward for military merit.
You can still discuss the innovations for a long time and complain about the developers' peculiar vision of the game balance (I am sure it will be put in order), but we will leave this for the forums. Most importantly, Relic Entertainment really managed to make an exemplary addition, and one of the best strategies of our time just got better.
Among other things, it is worth noting the fact that the Warhammer 40K: Dawn of War - Dark Crusade add-on works without installing the original game.
