Indie game storeFree gamesFun gamesHorror games
Game developmentAssetsComics
SalesBundles
Jobs
Tags
(+1)

It's impossible for me to complete one of the new achievements since I have permanent 30 corruption and I can't meet the pure version of my doppelganger. Is there a way to reduce corruption? 

(+2)

The pure doppelganger will show up when you have high corruption. (enough to get kicked out of the bastion)
I also have removed the corruption from those achievements for 0.7.3

Oh I see, I assumed that:
Low/No Corruption - Pure
High Corruption - Corrupted

Thank you for the clarification.

(+1)

The doppelganger is your opposite so :

High corruption - pure doppelganger

Low corruption - corrupted doppelganger

How high is high? And can I meet it again after defeating it?

It didn't trigger till I got overwhelming corruption (500 corruption I think?) and yes you can meet it again in the same run.

Thanks for the information.