Sounds good to me.
you missed my point - it would be time “available” to do art, not time “required” to do art. in a 4hr “from scratch” jam i wouldn’t even bother launching Illustrator - no time for it - just get to coding, and that’s ok too, but quite different from as originally proposed where pre-existing assets/libs were ok. (but it’s not my event, so whatever approach is fine by me, done with suggestions on how to run it, content to just wait and see :))
Just making a suggestion (and I actually hope to participate). If I understand the rules/concept, you’ve got four hours to spend sometime within the week to make your app. You can do one four-hour block, you can do four one-hour blocks, its up to you. If you want to spend that time making art, go for it. If you want to spend some of the time finding art thats up to you too. This is one of the reasons I suggested not announcing the theme until right before it starts. It’s your four hours. Use them wisely. If you preposition assets, outside of your four hours, then you’re using more than your four hours and that goes against the spirit of the game jam.
Also, if you do “find” art, make sure you have the rights to use it please.
Rob
wasn’t going to, but can’t resist 
i’m with Rob - don’t announce theme til last minute. set any rules you please, just make them explicit.
back on topic (theme suggestions not rule suggestions), perhaps worth perusing LD’s themes?
many are like movie/book titles – vague “conceptual” things, like “alone” or “islands” fe. while you might attempt to guess what such a movie/book would be about by it’s title (ie, the “obvious” interpretation) there are a hundred ways you could be wrong (ie, the “clever” interpretations), that’s where the creativity comes in.
very few specify any “mechanics”, like “build it up”. (again, no intent to pick on that one, just as example)
If it’s OK for all of you, I can announce a new theme when the jam starts with the latest rules. What do you say to that?
Count me in any way it goes, I’ll give it a shot. I like the idea of having a theme released just before the jam starts. Personally I’d like to try using some of the numerous plugins I’ve purchased over the past months to speed up development.
My wife and I host “Moth” inspired storytelling nights in our home and we give themes that can be broadly interpreted like:
treasure, mystery, discovery, disguise, mischief, elegance, invention, escape, release, demons
I think a broad theme released just before the start of the event would be a good way to go.
OK, I’m back! This time with the Corona Blitz page on itch.io. Here it is: https://itch.io/jam/corona-blitz-2017-01
I may still change some stuff on the page until the jam week so if you something that’s missing, please let me know.
I just joined even though I’m not sure I’ll be up for the challenge by the time already - but we’ll see 
@Michael, I’m glad you’re on! I’m pretty sure you’ll create something nice.
So far, 7 people(including me) has joined from the jam page. We’re waiting for you!
Since we’re way past the theme selection, here is the new topic for the “Corona Blitz 2017.01”
https://forums.coronalabs.com/topic/68166-corona-blitz-201701-april-1-8-2017/