I am very excited to participate in another contest. It's been a while since the last one.
I haven't thought of an idea yet, but hopefully I will find one soon. I want to stay away from the winter holidays, as there has already been a contest done for those. I also want to avoid holidays that only affect some people, unless there is something really unique about it.
I will probably write the program in C, as it offers the most features and has a huge speed benefit over TI-BASIC. I might use ICE, as I have never written a program in it before. However, the competitive side of me is probably going to make me use C because I will learn something no matter which language I use and I would like to win. But I'll be sure to give ICE a try at some point.

If my ideas for this contest are going to be anything like like the last contest, I will come up with a few easy ideas, and a few unique ones that are completely unlike what is usually submitted for contests. Then I'll work on the unique one until two days before and realize I have no idea how to pull it off. That's what happened for my last two CC20 entries. Hopefully I can see a complicated idea through to completion this time.
I might try to do something besides a game that is still interesting to do.

I'm not sure if I want to post my ideas here already in case others see something on my list of ideas that they would have had anyway and are convinced not to do it as a result.

A question on the rules (which is specific enough that it fits better here rather than on the contest thread): I am working on a small 2D physics header file for a few other projects (Data Wing CE and Floating Point CE), and I might want to do something with it in the contest. This is kind of a grey area, as the header is existing code, written by me, and is currently private, until I get a version with enough features for me to release it. However, it is also a library that has many applications outside any one program that I could write for this contest. I guess that maybe it might be allowed as long as I use a public release that anyone else in the contest could use themselves? Contest officials, what is your judgement on this?

Since you're saying that you're using it as a header, and you're still working on it, I don't see why not. If it is something that others may benefit from, you should post something about it in the contest thread. (or here) If it's something like a certain thing you use for all of your programs, then yes, you can use it. I personally, when writing in ICE, use a specific home screen and menu system. If it affects how the program/game functions, then you shouldn't use it. If it's just a home screen/menu, then you can use it.