I can, but then I would end up teaching the game. :)
At a very basic level, you draw a card every turn to determine which Japanese positions on the map will fire. For instance, here are a couple of battalions of US Marines on the right flank of the landing in my current game (which is NOT going well). The 7th regiment on the right is tasked with taking this jungle area, while the 5th regiment on the left should sweep across the airfield in front of them.
The AI cards are multipurpose, so they’ve got information splashed all over them. During the Japanese turn, we only look at the colored shapes in the dark stripe along the bottom of the card. For now, just look at the colors of the three squares and that final black symbol:
This means all yellow, red, and brown positions will fire, and if there are targeting limitations, they’ll prefer targets with a triangle. We resolve each color in turn, so starting with yellow, every yellow position checks whether it can shoot at a US unit:
The 5th regiment has overrun its yellow position, so they aren’t affected. The two yellow positions on the right can’t reach any US units. We know this because the colored dots in the hexes tell you which positions are vulnerable to enemy fire. You’ll note that yellow emplacement at the top center is smack dab in the middle of thick jungle. They can only reach the hexes immediately adjacent. So yellow does nothing because its fire can’t reach US units.
But then there’s a letter in some of the squares! These letters describe behaviors above and beyond simply firing at US units in range. Each of these letters is a whole range of different actions depending on the situation.
For instance, the letter A in the yellow box is for artillery, assaults, and ambushes, basically in that order. If the yellow position had artillery, they would fire artillery to damage one unit pretty much anywhere on the map with a triangle symbol. Since the yellow positions in the jungle don’t have artillery (most of the artillery is on a mountain range offscreen), the A instead indicates an assault. In the situation above, where the defender can’t actually see a US unit, it will first try to move to a closer unoccupied position if it can. Since I haven’t left it any gaps, it will close combat any position occupied by a US unit within three hexes. So in this case, that face-down chit on a yellow position will assault to try to retake the brown position occupied by 7th regiment’s K company:
If L company had managed to move one hex closer to the yellow position, the yellow position would have instead just attacked normally, and we wouldn’t have to fight a risky close-quarters battle in the jungle for a position we thought he had secured! (There’s a ton of randomness in close quarters battles.)
Then the red positions will fire or do R actions, which are reinforcement, resupply, and overrun (the symbol in brown doesn’t change behavior; it just means brown fire can snipe leaders). This letter systems allows for a range of behaviors that make the Japanese side play more dynamically with patrols, mortars, infiltration in areas you thought were secure, machinegun emplacements, arriving reinforcements, that sort of thing.
What this all means is that every position in the game, even empty positions, have a framework of possible behaviors you have to be aware of. If the 7th regiment sticks to the beach to try to take that blue position hemming me in on the right, it’s safe from direct fire from those yellow and green positions deeper in the jungle. But they can still harry me with mortar fire and ambushes.
It’s random whether it will happen, but it’s a very real risk as sure as direct fire from that blue position I’m going to attack. So I have to weigh the cost and benefit of securing the jungle as opposed to just pushing along the beach to the right.
So that’s what I mean by the AI doing unexpected things, but not randomly or stupidly. That yellow position in the jungle isn’t just going to sit there and wait for me. It has a range of sensible behaviors waiting to be triggered by the right combination of color and letter, and how it responds to that combination is determined by the situation I create on the map.