Those already familiar with
Dawn of War II know it snubbed traditional RTS features like base building in favor of pure squad-based tactics. Rather than follow the usual setup of build a base, collect resources, and build units,
Dawn of War II presented what I like to describe as a squad-based
Diablo. It wasn't exactly a hack n' slash RPG, but elements like XP, loot drops (in the form of wargear) and abilities certainly gave it the same feeling as most dungeon crawlers.
Warhammer 40,000: Dawn of War II - Retribution keeps the franchise on the same course, but true to the series, tries a few new things. The changes are always a good thing, but never without their problems. The big change in Retribution is the addition of mass scale army building. This doesn't mean the game has gone "traditional," but instead introduces a new scale of tactics to gameplay.
As with previous installments, you begin each mission by choosing four Heroes (or, if you choose, Honor Guards with an increased population cap) and outfitting them with gear. Once in game, you can capture bases, opening the option to create new units to bring into battle. Eventually, you'll unlock the option of dropping in turrets and other support.
Alternately, you can use points to temporarily buff your hero units, sometimes giving them the power of a full army for a limited time. Basically, you now have the option to either play the game using pure tactics or fall back on the option of amassing a small army. Either choice is viable and it's likely you'll switch between the two at least a few times. Everything is based on choices and they all have real consequences, which I really liked.
It's hard not to recommend Retribution. It's a phenomenal game, especially for the price. I wasn't sold on the concept of stand-alone expansions after Chaos Rising, but Retribution has made a believer out of me.