Naval, Air units and the theatre AI
One of the most consistent things we have noticed on our forum was people asking about invasions and the escorting of transports. You will have probably noticed that we tend not to answer these questions. This is mainly because it was an absolute waste of time. The AI you will see in Hearts of Iron 3, although drawing on our accumulated experience, was built from scratch. For that point of view we were never going to look to fix the Hearts of Iron 2 AI, instead we were looking to build a better one. From the first principals of design upwards.
Our first design decision, which you all know about, is the theatre. A theatre is a singular AI entity, and the highest level in the on the map AI for the control of units. A theatre holds not just land units, but air and naval as well. Having these under the control of a single AI entity meant it would seek to coordinate all the units types. Thus when fleets go to sea the theatre AI includes these areas of operation when thinking about where fighters should be looking to intercept enemy air units. NAVs sit on standby to support naval combats and also seek to bomb enemy units in ports and at sea.
This comes into its own with the invasion system. An invasion is no longer just simply shipping some units into an enemy province. It is a combined arms operation; it involves land units for the landing. Transports to move them. Naval units to escort the transports. Battleships to shore bombard the beaches. Air units to provide air cover and bomb enemies.
In fact the AI goes one better when planning invasions. If it has a target in mind it moves air power within range to support the invasion. Brings transports and supporting naval units to ports close by and moves troops to these ports in preparation for the invasion.
The AI doesn’t end there. If you are playing with theatre AI on it will kindly tell you that it needs transport to move things and ships to escort them. After all how do you expect the AI to do an invasion without them?
This is part of the power of the theatre system of air/naval/land in a single entity. World War II very much relied on a combined arms approach to victory and for our AI to have any chance of being an interesting opponent it would have to be able to do the same. Before the first line of code was written this was planned into our approach for the AI.