Dear friends :) I'm glad to announce that we finalized the major update of Invisible Apartment 1 which we were working on for a long time. You're now able to play part 0, 1, 2 and the new part 3 from within the same game as DLCs.
If you already purchased Invisible Apartment Zero as a separate game than we'll give you the keys for the new DLC for free - just follow the guide at http://steamcommunity.com/app/351790/discussions/0/348293292497416125/
http://store.steampowered.com/app/543220/
http://store.steampowered.com/app/532060/
http://store.steampowered.com/app/543230/
We also have a bundle which is really affordable at http://store.steampowered.com/bundle/1766/