Real-time battles, part 3: party AI

My last post about real-time battle systems looked at requirements for enemy AI. This third (and final) installment will deal with party AI.

To me one of the most significant differences between a turn- or time-based battle system and a real-time system is how the other members of your party behave. Old-fashioned time-based systems like Final Fantasy VII usually have random battles that take place in a temporary battle area. The advantage here is that the player can easily give orders to every member of the party during the battle, since only one party member or enemy can execute a move at any given time.

In a real-time system, things happen too fast to give explicit orders to each party member throughout an entire encounter. One obvious solution to this problem is not to have a party. But if you don't take the easy way out, you have to prevent the rest of the party from being a liability.

The common approach to party AI is, first, to give the player a way to switch control between active party members at any time during a battle and, second, to provide a short list of general behaviors for AI-controlled party members. These often give you three choices along the lines of aggressive, defensive, and support (healing and ranged attacks).

Unfortunately, these limited options usually result in party members that seem to get themselves killed (but only after using up all your items), and there is no way to customize their behavior any further.

Final Fantasy XII's gambit system finally offered a better and more fun option for party AI. By giving the player access to the if-then structure (e.g., if an ally's health drops below 50%, cast cure on that ally) of the party AI system (and by making it a part of the character leveling scheme), party AI became not only useful, but fun. Creating just the right combination of gambits became almost a game in itself.

One criticism of FFXII's gambit system, of course, is that the more gambit combinations are available, the less you have to pay attention during battles. You can literally run up to a group of enemies and go get a snack while your party defeats them. In some ways this is quite nice, but could be quite annoying for players who like finer control. Turning gambits off is always an option, though.

I haven't yet designed the party AI system for my game, and I don't know how I'll approach it. Some amount of control over party members' decisions is essential, but a more robust system would need to be carefully integrated into the gameplay and could distract from the primary character leveling system (which is going to be very cool, but I don't want to give it away just yet).

But until it's time to program party AI, I will turn my attention back to modeling buildings and other inanimate objects.