CodinGame is running a worldwide online contest tomorrow, Saturday November 23. If you miss this one another will be along in a couple of months and there are "training" games to hone your skills.

CodinGame runs online challenges as a sort of nerd matchmaking service. It describes its aim as:

to showcase programmers' technical skills to companies

Hiring interviews for developers routinely include coding questions to test a candidate's skills. But, as anyone involved in recruitment from either side of the interview desk knows, one of the problems with the entire recruitment process is that it tends to concentrates on qualities so it isn't always the best hackers who land the jobs that require their special skills.

CodinGame offers companies an alternative way to identify talent with its CodinGame Assessment, a paid for service that measures applicants ability to solve real-world programming problems.

It also offers a free service to job seekers, that of getting noticed by companies who are recruiting. In answer to the question, why participate it suggests:

• To demonstrate your expertise regardless of your academic or professional background.

• Because it's anonymous. Companies to which you have applied don't know your identity as long as you haven't explicitly accepted their invitation for an interview. Nobody knows who's behind a bad result.
  

Currently there are a couple of Open Challenges on its site and there are also over 20 Training Puzzles at 4 levels of difficulty which you can try out, discuss and also view the solutions from those on the leaderboards. The training puzzles also provide a good way to prepare for one of the WorldCup contests by familiarizing yourself with the test environment. 

You don't have to be looking for a job to enter one of its WorldCup competitions - just can do it for fun. It already has quite a big following as this infographic reporting on the previous contest demonstrates:

The details of the contest on November 23 are that is starts at 17:00 UTC and that there will be two programming puzzles to solve (estimated time required 1 to 4 hours). Fifteen programming languages are available: C, C++, Java, C#, PHP, Python, Ruby, JavaScript, Objective-C, Go, Haskell, Scala, Perl, Dart and Pascal (I have to admit to raised eyebrows at the last in the list!) and there's a leaderboard for each of the languages.

There's a Raspberry Pi for the 1st place winner and tee-shirts for the top twenty on the Global Leaderboard. But it is likely that at least some of the contestants will get the opportunity to interview at one of the 18 companies which have registered for the event, including Nintendo European Research and Development and CodinGame itself.

If you are job hunting its important to note that  for this contest' most of the positions are in France although Brazil and UK are also represented. If you are an employer and this method of identifying talent appeals to you it's too late to register this time around but another contest will come along in the New Year.