Lack of Organization...

[Kreekakon]

The most important thing when making a game is to be SURE 100% what you want from the game. It's easier with shorter stories where you can just memorize everything in your head, but with longer, and more complicated ones, you have to have a clear game plan (Pun intended)

Well I'm taking a course right now called "Video Game Planning", and while I won't go into extreme detail (That would be hella long), and these are the basics of a video game plan:

1. Game Title
2. Game theme
3. Game's background/backstory
4. Sources of Inspiration (Movies, other games, novels etc)
5. Game Synopsis
6. Game's Purpose
7. Game's Setting
8. Gameplay direction
9. Characters
10. Primary Gameplay Missions
11. What makes the game special
12. Who will play?
13. Where does the game's entertainment come from?
14. Game's World Setting and Lore
15. System Requirements (Not needed for Amnesia Mods though)
16. Flow/Steps of the Game
17. Entire Story from start to end.
18. Character Relationships, personality attributes, and motivations

The above is just an example at best for you to look at, but if you can make SURE what you want the game to be like, then you'll discover you'll have a lot more motivation, because you won't be wandering anymore, you'll be sure of what you want to do.