planet realms

hey all, trying to grasp how I would start to design the game. I do a lot of c#, DB and .net coding but not that major into game programming.

The idea, a simple game.

1. a space with multiple planets (I will probably randomize the planets and sizes out on the playfield)
2. every planet has a max amount of bases where they can build ships
3. they can build a max amount of ships per planet depending on size
4. simple design and play
- Say a planet size 10 can have a maximum of 500 ships. player can select 1 or more planets in team that he owns and once you reselect the further out you pull, larger amounts of ships you will send hurdling towards another planet and if you send enough to destroy their defenses and ships you get the planet. if you select say 1 planet then press and hold mouse button on planet and pull say 10 clicks out from planet you send 100 ships but if you pull 50 clicks out you send 500 ships is the idea.

Very simple game. Should I make a prefab planets with various scripts indicating the various data such as max ships, owner etc. and then randomly choose from a list of prefabs?

Also I should probably use a singleton as a main script or would this be necessary, can I just use a regular main script?

Just having a little hard time where to start and how to build it. I will make it AI based as I am ok on AI coding.

Does anyone have any pointers where I would best start, how to approach the coding and design etc.

Any help or suggestions are appreciated.

/Thank you.