The reasons why you might want to be very corrupt or very pure lie in the traits unlocked by the Corruption bar. Essentially bolt-on abilities for your characters, independent of its levels (the level cap, by the way, rises from 20 to 30, with each of the skill trees extending correspondingly), these are interesting abilities which all have unique trade-offs in their power. You might, for example, get a powerful new attack - but when you use it, it drains your own health.
The Corruption meter allows Relic to add even more customisation to the game's RPG-style character sheets, but without adding too much extra complexity, since the decisions you make regarding Corruption come through the flow of play rather than being left for you to puzzle out on the character screen itself. It also hints strongly at Relic's other big change in Chaos Rising - a fundamentally new approach to how it creates missions.
This is another aspect where the team knew it had a weak point that needed addressing. "When we started hearing feedback about the Dawn of War II campaign being repetitive, the missions being repetitive... We just thought, okay, that's got to be one of the key things we try to improve," Lydell says.
To that end, while the length of the single-player campaign is quite respectable - "it's about the same length as the first Company of Heroes, around 15 hours" - the structure is quite different to DOW2. There are only 15 missions - significantly fewer - but each is more complex, boasting several key decision points (which often influence your Corruption score, depending on how you tackle them) and a host of sub-objectives which build to a climax. From Lydell's descriptions, it's a far cry from DOW2's somewhat-pedestrian structure of fighting through a dungeon and then beating a boss in every single level.
