This is a guest review by LudovicRetribution is a must for fans of the Dawn of War series, peppered by various elements bound to make fans of the series grin with joy, the new campaigns being the least of such. It is not without some flaws, but in favour, the flaws are very easy to overlook in light of all that the game does bring, and that is good.
First of all, let me start this review by saying that despite all changes, Retribution hasn't reinvented the wheel. Rather, what we're looking at is still nonetheless a radical streamlining of the campaign's mechanics and structure, as well as quite a few nice tweaks and additions to the multiplayer, a notable addition being the new Imperial faction, the Imperial Guard. Still, all in all it remains quite good fun and though the campaign has its good and bad points, in my opinion Retribution is certainly a fun and most entertaining romp.
Single-playerThe single player campaign is solid. In fact, this is probably where Retribution departs the most from previous Dawn of War 2 releases being where the more radical changes to the game can be felt. In fact, the rest of the game actually did pretty much remain the same with the exception of the single player, though there have been tweaks here and there and some additions, I will begin with the change to the campaign's mechanics.
Let's start by saying again they are big.
For the very start, you aren't restricted by playing only the Space Marines for this campaign, now you have the choice to play all six races, the new Imperial Guard included.
The way you play the campaign has also changed. Like in the old games, you have many champions with unlockable abilities and wargear to outfit them with. Notable additions is the streamlining of how abilities are unlocked.
On another note, the only thing that slightly bothered me was how only a very few characters would now change appearance when equipping new armour, unlike Dawn of War 2 where all armour had a unique appearance, further adding to the customization of a hero through their visuals on top of their stats. Being only a minor cosmetic issue, this is far from spoiling at all the game. Another tweak is the fact that you now lead a full army, allowing you to recruit "conventional" units to fight alongside your heroes on a mission, summoning them through reinforcement points and with new "Stronghold" capture points allowing you to recruit vehicles as well for the mission.
But if this was all, it would make for a poor campaign if the missions themselves were lacking. Fortunately it is a nice thing that another area to see a lot of revamping was the approach to the missions themselves.
I won't say much, as to not spoil it for people who haven't played through the campaign yet, but where Dawn of War 2 had much more missions, many amongst them actually lacked a fair bit in variety, ultimately often summing themselves up to a romp - smashing mobs standing in your way until an eventual mission's "boss"... only to rinse and repeat the same process the following mission.
Retribution has a much more linear progression, most missions even being shared between all of the factions (though played from different viewpoints). This time each of the missions actually have unique goals and events occurring throughout the mission when compared to the sometimes "cookie cutter" missions of the original Dawn of War 2.
I won't say much, but expect to be chased by monstrously huge nigh-invulnerable units, escape inevitable destruction and to listen to most amusing quotes in the Ork campaign (one of, if not my single most favourite take on the campaign so far, starting with the first mission introducing you to it)... all of it leading to a much awaited showdown for first-time fans of the series toward the end of the campaign.

I realized that giving the same overall campaign to all races wasn't necessarily a bad move. To put it in another way, the campaign can be indeed seem as a game mode of varied challenges, like a multiplayer game. And like in a multiplayer game your choice of race thus comes to preference rather than their campaign. Each race plays differently thus it forces you to also think differently to tackle the various challenges of a mission. An example was when I played again as Chaos on a mission I had beaten in the Space Marine campaign already, due to the different hero, units and wargear selections I suddenly found myself having to think much differently once I remembered that Chao did not have access to a jump capable hero or a heavy weapon commander like I had geared my Force Commander as the Space Marines - due to the differences between Eliphas and Appolo. All in all, it has only served to better my opinion of the design decisions that were made for the campaign play in the expansion, and with the different hero -and- unit customization (each completed missions, you are generally given a choice between unlocking a new piece of wargear, a new unit, or an upgrade to an existing unit), it only adds to the replayability by taking a specific global strategy in one playthrough and then switching it to an entirely different one with a radically different choice of unit unlocks the next.