Brainstorming an idea

Team composition

The game you are making must fit the team, make sure to adapt what you propose so that it works with your team composition and strengths.

Example: 

• Your team has 5 artists but 0 designers: make your game rely on visuals, and keep the gameplay interaction as simple as possible (ex: Journey, Abzu, etc.)

• Your team has 4 coders, 1 designer and 0 artists: make a technically-focused (but less visually appealing) game. (Ex: Tetris/World of Goo, etc.)

Scope and focusing your idea

Be wary of scope as well, it's better to aim for less and do it right than not being able to finish or rushing the game to reach the finish line.

To that effect, I strongly recommend focusing on 1 core mechanic. “The core mechanic in a game will usually be the purposeful interaction that occurs the most frequently. In a platforming game, this is usually jumping. In a shooter, it is usually shooting.” (Charmie Kim, read the article here).

Example: 

• Tiny Wings (Andreas Illiger, 2011): has 1 mechanic (jump), 1 button (press the screen), and would be easily buildable in a short amount of time.