The developers of Hearts of Iron IV have pushed an open beta that previews the anniversary patch. It brings a range of fixes and play-facing tweaks alongside a major redo of naval AI and performance work.
Fleet behavior got the most scrutiny this time. The studio admits the naval side has been troublesome for a while: when fronts shift quickly the AI often lags, and it hasn’t used its ships efficiently.
They also pointed out something deliberate — the AI won’t try to build obvious “meta” ships; historical-feeling fleets are preferred over cookie-cutter powerhouses. Still, the team has reworked several bottlenecks, e.g., research priorities and how tasks get assigned to individual ships.
Strike groups are now rebalanced more frequently, with newer hulls pulled from reserve pools so fleets stay combat-capable longer. Wartime movement is still constrained, though; that prevents single ships from wandering the map in chaotic ways.
Repairs received a noticeable overhaul. Instead of blindly following automated rules the AI now weighs options — nearest base vs. a safer harbor, for instance — and can swap damaged capital ships out quickly from reserves.
Response times improved after removing an extra decision “layer” that tended to delay reactions. Threat priorities are recalculated faster, which makes fleet behavior feel snappier in practice.
A couple of odd bugs were fixed separately: bad base-choice logic, and a runaway lend-lease bug that could bloat shipments and lock the AI into nonstop convoy production.
The update also adjusts combat balance. Strike fleets won’t take fights opportunistically while en route anymore, which used to let players intercept them easily. Aircraft HMGs were toned down, and some setups now carry reliability penalties.
Work on naval AI isn’t finished, the devs say, but you should already notice fewer weird fleet moves and more actual naval encounters — not a cure-all, but a step in a clearer direction.