I was looking at a battle issue reported recently that battle reports were not always being displayed. I’ve had reports before that the AI Lords don’t appear to engage in battle the same as the original, but I have tested this many times and not been able to find an issue other than the AI being unpredictable and a little shaky.

I had recently done some testing while adding the new game rules in place and had my lords attacked, and indeed failed an approach of lord and been attacked, and attacked a lord and battle had commenced, so on the whole it seemed to be working.

I poured over the code again to check the AI conditions of battle and noticed something interesting. The rule is that if the lord can’t walk forward and it is dawn and they are not blocked, then there is a 50% chance of them staying in the current location and ending their turn.

Analysing that a little; blocked means exactly that, they cannot move in the direction they want to under any circumstances. This is usually because of Icy Wastes or there are too many people in the location. Can’t walk forward is usually a transitory check, something in the location they are in or entering could potentially stop them entering, but nothing that would break the game. The Dawn check is just helping to differentiate moving into a location during the turn from moving out of a location at the start of the turn.

The code that makes those decisions is separate from the code that is handling the AI Turns logic. So I went to look at that to check under what condition the lord could not walk forward, and the thing that caught my eyes was – if there is an enemy in the current location. Combine that with the checks in the AI Turns logic and what you have is, there is a 50% chance that a lord will leave a battle at the start of his turn, but if they enter a location with an enemy they will always stop to fight.

The problem was that this flag was being reset by another piece of logic which was actually more to do with the player and not the AI, and also some shared LoM logic. The net effect was, if you attack an enemy lord, or have a failed approach, then the enemy will pretty much always move on and not engage. Now, this seems counter to what my testing has shown, so I can only posit that there was something else happening in these situations that was keeping the enemy at the same location.

Once I realised this it was a quick fix to isolate the piece of code that was overwriting the can’t walk forward flag. However, this then highlighted another bigger issue, and that was that the lord was not considering the enemy as their enemy, and thus the trigger was not occuring.

Again, I checked out the area of the code that handles this, and clearly it was based on LoM, in that Luxor is the friend, and Doomdark/Shareth is the foe. But this does not take in to account the multi-race nature of DDR. So what in effect was happening is that the AI was not really considering the players lords as enemy, or indeed not always correctly considering the enemy AI lords as enemy, which means they would often over look them. Obviously there were fighting, but again I think other issues were causing them to stay in the location of another lord. And as long as multiple lords are in the same location, the battle algorithm would get the friend/enemy check correct and they would fight.

Now, this looks like it has always been wrong, ie: nearly 10 years since I released the games. But I suspect the problem is actually due to the merging of the code bases and likely crept in in the later stages of v1 and then rolled over in to v2.