What are these UF challenges?
How do challenges work and how can I participate?
Can I help promoting the challenges in some way?
What if I have an idea for a future challenge?
You can find all this information and more in the
Ultra Fractal challenges FAQ, which is also part of our very first UF challenge, the one for February 2011.
If you already know the rules, then you're good to go - read on for this month's challenge!
Previous editions:
You can find all of the previous challenges in this journal. Please keep in mind that the challenge rules changed after the 26th edition!

Links to ALL UF challenges (updated periodically!)Since the UF challenges are growing in number, instead of linking them all in each new one, I thought I'd make a collection journal for all of them. This will contain all challenges held so far, from the newest (top) to the oldest (bottom), all conveniently thumbed for you! It will also be updated each month so that ALL challenges are reachable from here, even the newer ones. And this journal will of course be linked in every challenge, to keep them all connected 
Sadly, challenge #11 is apparently a broken link. It's the only inaccessible one so far, though, so I may be able to restore it someday, if you guys wish me to.
Let's go!
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Now we can go on with the last challenge's results, and then I will introduce this month's challenge to you all.
Here is the
December challenge, themed "Holiday Bash". Unfortunately, only two deviants participated:
But they still managed to deliver very Christmas-sy works! =
Leichenengel's red and green chromatic feast is a twist of different shapes, while ~
Gerda1946 presents us with a monochrome electric blue and a stellar leitmotif. Both works greatly echo Christmas trees, shapes, and colours.
So they get featured on par, unlike you lazy folks who didn't even care to make a single holiday fractal in a whole month. Ha!

Well, childish pointless observations aside...
We're done for December. (And for 2011 as well!) On to January!
Ultra Fractal monthly challenges Redux
Challenge #12: January 2012
January's challenge will be a Formula challenge - its title being Pearly Perlin!
We're going to start the new year with a simple guideline of a somewhat difficult execution: making good fractal art with the Perlin Noise formula, found in aho.ufm in the UF formula database. You may use any colouring algorithm and/or mapping of your choice, but all fractal layers MUST use the Perlin Noise fractal formula.
While it may seem like a rather strict rule, it really isn't, as it is a very versatile formula which may bring to unexpected, beautiful results!
You can see some of my Perlin abstracts here:
A lot of artists have proven themselves very skillful at making wonderful Perlin-based fractal art. These are just some of the examples!
Remember: to enter the challenge, post your deviation's link and thumb in a comment of this journal. ALSO: PLEASE MAKE SURE YOU LINK THIS NEWS ARTICLE IN THE DEVIATION. (Sorry for stating it so strongly, but I've had lots of people saying they'd enter the challenge without even stating it in their deviation comments, so I figured I'd better add this specification somewhere!)
Please spread the word by advertising this news article - we definitely want more participants. The more, the merrier!
Be sure to watch out for next month's challenge too, as it will be our FIRST CHALLENGE ANNIVERSARY!

This challenge's deadline is
January 31st. Ready, set, GO!!!

[link]
If you don't like this one, i have 40 or 50 more! It was a fun filled exploration!
Glad you liked the formula so much!