Step 1: Conceptulalization/Fleshing
These two things start off the game on the right track with everyone. They show how the game could be like, and describes it. For example: Lets say we are making a game called "Sonic 4: The Death of Sonic."
It can be as simple as this: Sonic 4 is a game for 1-2 players that shows the death of Sonic.
Or, It can be as advanced as this(or even more!): Players: 1-2, 1 player at a time.
Characters: Sonic, The Grim Reaper, Tails
Object: Too keep Sonic alive. Sonic has to walk fast to dodge the Grim Reaper on his tail. He must get to the end of the level and get a life-force for going on to another zone.
Stage 1: The Cemetary
Stage 2: The Great Beyond
Stage 3: Tails City
Stage 4: Mushroom Kingdom
So, things could get complicated even at the start. The more you know about the game, the better you are off starting the game! They can ax a game and start from scrach here very easily. This is the easiest step.(But of Course!)
Go To Step 2: The View Mode