If you own specific older DLCs, the 1.10 update also provided "free" bonus content for those expansions:

: The Heavy Cruiser 3D Asset Pack , which was previously exclusive to the Colonel Edition of the game, was merged into the base game for all players.

The was the free patch released alongside the Battle for the Bosporus country pack for Hearts of Iron IV . While the main expansion adds paid focus trees for Turkey, Greece, and Bulgaria, the free update provides significant refinements to existing Balkan content and general gameplay. Key Free Features of Update 1.10 ("Collie")

: Received a reworked focus tree for Yugoslavia and tweaks to Romania's starting position.

: Changes were made to how naval supremacy scales, affecting how players control the seas without needing specific DLC mechanics.

The "Collie" patch focused on improving accessibility and expanding the game's map without requiring a purchase: