You, sir, are an insane person. So you want to stop this now? Because, let's face it, when you freeze it now, you will never finish it.

So here you are, with a pretty promising game and a huge fanbase (I mean, just read this thread, it's ridiculous), and yet, you stop? I know that you say from yourself that you have problems motivating yourself, but come on. Wouldn`t it be enough to read this thread? I never even get a fraction of this feedback, yet I can still motivate myself with the one or other encouraging comment.
What you need to do before doing anything else is finding a way to keep motivated longer. Make a list in which you write what you've done each day and reading it will motivate you. Don't delete things you've done from your To-Do-List, make them red or something, but keep them on the list. It also motivates. MAKE such a list
You need to improve the planning. The project was probably too large to be ever finished by just a single person, but why dont you finish what you've started so far, post it here and let you motivate by the dozens of comments sure to follow?

Aah, what a shame. Of course, many of us have a few "frozen" projects (myself included), but tihs time, with the amazing amount of feedback given and no other reason to stop other than just no motivation (no technical issues or something along these lines), its just too sad. I had to say something. Thank you.

All I can hope is that you only posted "Project Frozen" because you hope for many comments that motivate you again. In this case, let this be number one.