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It's a common problem when working with a game framework to wonder where and how to organize your logic. Luckily, Mischief comes with a few tips and guidelines on the subject.

Modularily is highly encouraged in everything you do. You should strive to design your codebase so that each part of it can be easily plugged in and out without affecting the functionality of anything outside of it.

For instance, you may have a PhysicsPlugin that adds physics to your game, a RenderPlugin which renders objects, a LevelPlugin that spawns your levels.

main :: IO ()
main = do
  app <- newApp
  addPlugin @PhysicsPlugin
  addPlugin @RenderPlugin
  addPlugin @LevelPlugin

Ideally, each of these plugins add their own independent features. So if you were to remove physicsPlugin, your entities simply wouldn't move and collide anymore, but the rest of the app would work just fine. Dependencies between plugins at the same level should be avoided. For instance, PhysicsPlugin should not ever depend on RenderPlugin.

Internally, PhsyicsPlugin could also be subdivided into its own plugins with separate roles:

data PhysicsPlugin

instance Plugin PhysicsPlugin where
  deps = [dep @CollisionPlugin, dep @MovePlugin]

And these should follow the same principle of independence.

Of course, complete modulariy may just not be possible or desireable at points, but we consider it to be a great standard to look up to.

We encourage placing each plugin in a separate module / file. It's also desireable for the module hierarchy to follow the follow the plugin dependencies. If the Player plugin in MyGame.Player depends on the Health plugin, the latter is ideally placed in a MyGame.Player.Health module.

We also encourage defining components locally in the module that uses them most. If multiple modules at the same level use the same component, consider placing it in a separete Common module.

Following some of these guidelines may be incompatible with your type of project or the way you prefer to organize things. That's fine!

The most important thing is to try and keep it all consistent throughout your project. Set clear guidelines and rules for yourself and stick to them!