The latest patch for Far Cry 4 rolled out a short time ago today. It's a hefty one, coming it at around 1.1GB (at least on the PC), but it adds some neat functionality to the game. Namely, it adds the ability to play custom maps with a co-op partner.

Changelog for Far Cry 4 for February 4, 2015

All Platforms [PC, Xbox One, Xbox 360, PS4, PS3]
In-Game Editor [IGE]
- IGE Co-Op is now live!
- Fixed various Gameplay functionality issues with asset placements
- Fixed various Gameplay functionality issues with the Map Browser

Co-Op
- Integrated Outpost Master in Co-Op
- Fixed various client connectivity issues
- Fixed various Host/Client replication issues

Load and Save Files
- Fixed various checkpoint placement issues

Vehicles
- Fixed the occasional issue with vehicle placement

Matchmaking and PvP
- Fixed matchmaking stability and general issues with PvP
- Fixed inconsistencies with XP in the load-out menu

Gameplay
- Fixed spawning issues under specific circumstances

Xbox 360 and Xbox One
- Fixed co-op matchmaking issues when user’s signed in as an inactive profile

(via Ubisoft)