Agile Milestones?

During my daily job I'm a game producer/project owner and I would like to tell you my best way for organizing goals.

Currently I'm working on prototype but what I would like to accomplish? The simples way is to create goals that I will try to reach and check if every goal is acceptable. 

Take a look at this example:

Sci-Fi Prototype Checklist.

Goal/Quotes	Description	Approved	Players Rating
Killing enemies in this game is awesome! Never seen something like that on Mobile. I love to kill enemies!	Feeling from shooting and killing enemies.	NOPE	0/10
I want to play again!	Game isn't boring. Lot's of replay value. Game isn't to long.
You really need to think which traps you will set and which weapon you will use during gameplay. Strategy is major part of the game.	Gameplay diversity.
Graphics is outstanding!	Props, VFX, tekstures, materials, scenes.
Sci-fi mood is great!	Ambients, sound, graphics, effects.
I know how to play, and it's easy.	It's so easy that you don't need tutorial.
Placing traps is easy and intuitive.	Camera, description, UI, controls.
Powerups are really useful!	Description, UI, using, effects.
I don't have any problems to understand game goal.	UI, summary screen, hi-scoring. In-game communication.
I don't have any problem to understand how to shoot/change weapon and which functionalities weapons are providing.	Controls, UI, “tutorial”, effects.
I know exactly why I want to play again.	UI, in-game feedback.
It's easy to understand enemies mechanics.	Animatinos, weak/strong attributes, UI.

You should print that as I did and look at this every time you work on the game. 

As you can see I'm focused only on gameplay and fun. This is the main goal of every prototype/milestone. If something isn't fun and playable you shouldn't be creating it.

You can create more detailed checklist for you/your team, but you should have TOP 10 main goals/quotes visible to everyone. 

When I will be thinking that prototype is finished I will check if I can give 10/10 as score on that checklist for everything. If yes - then will move to more (Will try with 100 but it's always better to have more feedback) people and check how they will evaluate the prototype. Of course I would need to create target group first and don't send build to someone that isn't in my target group. You should get feedback outside your target group as well but mainly focus on your target.

Tasks vs Goals vs It's Done?

This comes only from my experience so you don't need to agree with that.

Basically goals are great for both experienced game developers and juniors. Goals are more "creative" and let you think about what you will do to accomplish something. (yeah: will let you learn!)

Tasks is something like "draw a point at X:150, Y:70" - creative? Don't think so:) Tasks can destroy communication because you know exactly what to do and you don't need to create brainstorms/talk with other developers. You can but you don't need to :) Tasks can be really helpful when reporting bugs and fixing the game. 

I hate not being creative so I "hate" tasks. Game development is always creative work and great games comes from being creative. 

Of course you can create tasks and assign them to goals (how I will accomplish the goal? Which tasks I need to do? ) - only for you and tracking your progress.  Making progress = making smiles on devs faces.

What I'm doing in my job is to keep goals vs tasks balanced. (new features: goals, fixing issues: tasks)

When it's done? When team is happy about it (10/10 score) and when you will get great feedback from other players inside your target group. Then you can move forward. 

Milestones?

Basically major quotes/goals should be visible on every milestone you want to do, so your game will have great quality all the time. You should create a lot of milestones with release date/budget. (prototype, vertical slice, E3 build, First Apple build etc etc you don't need to create Alpha/Beta milestones only) I don't have budget so I don't have any release date, but it's always better to work with dates. You will have more motivation and it will make your think twice how you want to do something.

To summarize - this is how I will proceed. I will be working on prototype to the point that I'm really happy about it. After that I will create an build and sent it over to my target group.