I was checking up to see how your game was going and saw that you may need a little help. I feel you on how you are having problems finishing your game (I don't think I completed a single full featured game). You may have heard some of this stuff before but maybe something might help.
Your problem seems to be coming up with ideas and less on implementation. I have it the other way around which results to frustration on not being able to implement my ideas. I will think about coming up with a story but I'd like at least some idea of what you'd like. Something I would recommend is to keep a notebook or a small journal with you to write down ideas. Simple, stupid, and it every one stresses this even for all types of hobbies n stuff, but it does work and will hopefully help. You said you are not a big gamer but if you watch tv shows, movies or do play that occasional game think of what you like about it. Is it the story, atmosphere, weapons, customization, gameplay, tactics and what not. What genre do you enjoy? Do you like action for more intense play, comedy bringing a lighter side to the game, horror with demons and zombies and stuff, or even romance. Try breaking down the plot into a simple form of whats going on. Keep that notebook near your bed and make sure you have a pen so your not trudging through your house looking for one when you got that aha moment before you fell asleep.
Just think of how many shows and games use these same ingredients over and over again. \/\/\/
Mario = Fight your way to save the princess
Die Hard = Fight your way to defeat the main antagonist
Clue = Find out who committed the crime with the evidence you gather
One of my all time moments was going into vaults for the first time in fallout 3. Figuring out what has happened to a environment where its inhabitants are missing or changed in some ways is what really got me. Particularly that one that was an experiment to test the inhabitants reactions being givin psychedelics without them knowing and finding out what happens to when the vaults order of power starts breaking down and everyone starts going insane. Man, seeing the hallucinations and realizing its effecting you too was one of my all time favorites in a game. Another one at the top would be vault 11 in New Vegas (wont spoil since its the latest one and is really good) particularly the super vague conclusion of the whole vault which may have gone under the radar and you'd never have a second thought. If you never plan on playing I suggest looking that one up. I spent hours looking all over when I found out
Writing a story about something you like is important because you are going to be the one spending your time building the game around it and spending a whole lot of time play testing. Even if someone hands you a story for your game and you use it just because its all you got. Do you want to spend all that time and frustration going into something you don't care much about. Another thing is to build up excitement (even if it is faked) whenever you can to help you push forward to finish. Try and make writing dialog for all those npcs a big triumph or better yet make even creating one have that same feeling. Showing family, friends, and even people on random forums
will help you keep from dropping everything. Also while your at it ask them what they think and ask if there is anything they think should be in the game or what kinda of stuff they like in general. Also I am one of those guys that will say not try to do something new until you get several games under your belt especially when it comes to games with alot of substance like rpgs, it'll break you like me and so many others. Another thing is to try keeping away from the idea of minecraft cause a game like that is hard to get right since it is almost solely based on crafting and it is up to the player to get the fun out of it. Also I feel that unless it continually gets updates or has multiplayer it gets old pretty quick.
Like I said if I come up with an idea I'll let you know if you are still working on it. I have/ had the hardest time finishing games and coming up with ideas which lead me to reading up alot on it. So hopefully you got something useful out of all this also don't give up the game looks great so don't let this one go man.