I like very much this initiative prepared by Eduard Matito,
Ferran Feixas and Henry Rzepa for the next CB2017 Conference in Aachen, September 2017. This is how the Unusual Chemical Bonding Challenge works:

http://cb2017.rwth-aachen.de/ChemBond_files/chembondslam.pdf

The challenge is already available online on the wiki website:

http://dipc.ehu.es/bondslam/index.php/Main_Page

From the wiki website slides can be downloaded and you can also interact with “unusual bonds” proposed by other researchers. Everyone is invited to participate in this challenge; the deadline is August 31th to be discussed during the CB2017 conference. The Organizers say that “even if you’ll not come to the conference you
can perfectly contribute to the challenge on-line only. Your contribution
will be briefly presented by the chairmen of the session during the
conference.”  Enjoy and participate!