Hello!
We will be offering upgrade discounts to prior owners of PD Howler on Steam through bundles. At this time anyone who owns PD Howler 10 can upgrade to 11 with a 50% discount. An upgrade option for 9.6 users will be live soon. We hope you enjoy the new features!
PD Howler 10 Upgrade Bundle:
http://store.steampowered.com/bundle/3373/PD_Howler_10_Upgrade/
PD Howler 9.6 Upgrade Bundle:
http://store.steampowered.com/bundle/3408/PD_Howler_96_Upgrade/