At GDC 2016, Guerrilla Games Art Director Maarten van der Gaag spoke at a panel focused mostly on outsourcing art assets and towards the end, as a nice reward cookie, there was an image showing artwork from Horizon: Zero Dawn.

You can see it at the bottom of the post, showing what kind of level of detail we can expect for an apparently mundane element like a roof in a location named Nora.

From the panel we also learned a few interesting concepts:

• Killzone: Shadow Fall included 14,000 art assets, almost all of which were outsourced to over 100 artists at several studios.
• The reason why Guerrilla outsources so much is because their core business is making games, not assets.
• Many that don't know game development often think that outsourced assets are of lower quality. That's not true. van der Gaag mentions that one of the pros of outsourcing assets is very high quality.
• Outsourcing studios have very skilled artists when it comes to execution, but they won't do visual design or art direction, this means that outsourcing requires careful preparation.
• Preparation of briefs for outsourcing studios takes a lot of time and effort.
• It also requires several concept artsts. Guerrilla's concept team currently includes 17 concept artists of which 7 are permanent staff.
• With the right preparation and attention even junior staff can make high quality briefs.
• The outsourcing pipeline can take longer than some expect between the beginning and the finished assets:
  • Style Guide: 2 months.
  • Briefs: 1 month/batch.
  • Touchups: 1 week/batch.
  • Outsourcing: 2 months.
  • Integration: 1 or 2 weeks
  • Total: ~6 months
• Creating comprehensive style guides is even more important with a new IP like Horizon: Zero Dawn, as it's less understood within the studio.
• Multiple disciplines are involved:
  • Concept design.
  • Narrative design.
  • Game design.
• Lack of quality in the results is normally the fault of the original studio, not of the outsourcing studio.