Before i started my game concept art i was looking through different game ideas using articles like this one but then i decided to change my design style because it looked to confusing and time consuming and i also didn’t have the skill to do such complicated designs like these.
I also used this magazine which helped me look at different body positions which helped me know to draw your arms and legs in different types of positions for things like the animation in game.
I used this page to see how i could draw a weapon in someones hand in detail because my game is a first person shooter where you will be seeing the hand and a gun for example like this.
Original book: Creating the Art of the Game
Author: Mathew Omroick