I've been working on a little game for the last few months, trying to approach it as a software engineer and employ best patterns and practices in my coding. I have gotten to the point where I have to distinct elements in my game.
The Game Logic: aka business logic. Its the meat of the game rules. It contains all information about game objects (such as Character, Weapon, and Item class definitions). It contains the game world as far as rules are required; mainly so Characters are aware of the world they are in, and who else is in it. It contains a chunk of logic use to determine how Fighting is resolved between Characters, as we as other game actions requiring rules. It contains my AI implementations. So in reality it's a combination of Class definitions and Service logic.
As it stands, the Game Logic can actually play out a game without any interface. All I need to do is create a World, add some Characters to it, assign some AI's to them, then in a loop tell their AIs to run. The result of each AIs action is reflected in the states of the Characters (eg, if damaged, health is reduced), and a summary of what happened is returned by the execution (which is intended for the UI to make sense of what happened).
The Game UI: which is using Cocos2d-xna for WP7. It contains definitions of all the different animations. It takes in inputs and sends the to the Game Logic, and renders its results.
As it stands, as well as all UI components for a Character (textures, sprites, animations) a UI Character also contains a Begin method which executes a Cocos2d Sequence (ccSequence) to do two things 1) Execute AI and render result for this Character 2) Re-Execute the sequence (essentially its own call back loop for executing actions).
The problem I keep running into is, the more I try to keep these two layers separate, the more they need to come together. E.g., my UI Character which is used to render what the Game Logic character is doing, so it needs a reference to the Character object from Game Logic. When this Character's AI attacks someone in the Game Logic world, the UI needs to know what happened. This works fine for rendering its own Animations based of its results, but to know what to do for other Characters affected by this action is difficult as I dont have reference to them. At the moment I do this by queuing up Pending Animations in the other character's Game Logic Character and render it when that character next executes, but this is anti SoC (Separation of Concerns) as it now contains something specific for the UI to focus on.
I don't want the two projects to merge into one where a Game Logic Character contains all things UI as well, such as animations and actions. Is there a nice clean way that is used for this separation? Ideally something that works nicely with Cocos2d's Action pattern?