At some point when working as a Game Designer I started putting down the things that kept coming up from project to project, from game to game. This notepad file ended up to be this checklist, which will help you during production not to forget what is needed!
Here we go! Hope it is valuable to you :)

Could I add difficulty setting? Would it give more value for the game?
Could I add character selection? Would it give more value for the game?
Should the characters have different attributes?
Should there be collectables?
Do the power-ups work together and create new combinations to play the game?
Do I have variation in score for level, score can always be improved?
Can the game be played in more than one way?
How will the tutorial work?
Can the tutorial be restarted?
Do achievements force you to play the game in a different way?
Check my scoring, how does it work, does it affect your game? Is it obvious and rewarding?
Should I include combos?
Does the player have a meaningful goal in the game?
Is the goal clear to the player?
How will a good player do?
How will a bad player do?
Would the game be more fun played the opposite way?
Can I explain the game easily?
Do others get excited about it?
Will my help texts be long and very complicated?
Do the options I provide, provide risk and reward kind of meaningful choices?
What will the hud require? Really, all that?
Do people understand what I want them to do?
Do players understand why this and that happens in the game? If not, how can I make the core more clear?
Do I have a lot of secondary things hiding the fact that my core does not appeal or work?
Do I fix features with new features?
Have I utilized the theme I use or is it just glued on?
Do I reward the player enough? No. How could I reward the player more!
Does my game include 15 secs wow effect in the beginning? It should!
Do I response to all actions the player does?
Does my game include a challenge - or is it just a click through adventure?
Does the game include long term goals!
I've done market research already months ago.
Is it still FUN? Be honest!

THE CHECKLIST

Could I add difficulty setting? Would it give more value for the game?
Could I add character selection? Would it give more value for the game?
Should the characters have different attributes?
Should there be collectables?
Do the power-ups work together and create new combinations to play the game?
Do I have variation in score for level, score can always be improved?
Can the game be played in more than one way?
How will the tutorial work?
Can the tutorial be restarted?
Do achievements force you to play the game in a different way?
Check my scoring, how does it work, does it affect your game? Is it obvious and rewarding?
Should I include combos?
Does the player have a meaningful goal in the game?
Is the goal clear to the player?
How will a good player do?
How will a bad player do?
Would the game be more fun played the opposite way?
Can I explain the game easily?
Do others get excited about it?
Will my help texts be long and very complicated?
Do the options I provide, provide risk and reward kind of meaningful choices?
What will the hud require? Really, all that?
Do people understand what I want them to do?
Do players understand why this and that happens in the game? If not, how can I make the core more clear?
Do I have a lot of secondary things hiding the fact that my core does not appeal or work?
Do I fix features with new features?
Have I utilized the theme I use or is it just glued on?
Do I reward the player enough? No. How could I reward the player more!
Does my game include 15 secs wow effect in the beginning? It should!
Do I response to all actions the player does?
Does my game include a challenge - or is it just a click through adventure?
Does the game include long term goals!
I've done market research already months ago.
Is it still FUN? Be honest!

EXERCISE - APPLY THE CHECKLIST

Easy - 1 hour

Start Learning

EXERCISE - APPLY THE CHECKLIST

Easy - 1 hour

Start Learning

EXERCISE: DO YOU HAVE THESE

Easy - 15 mins

Start Learning

EXERCISE: DO YOU HAVE THESE

Easy - 15 mins

Start Learning