I have already started making my tool after LD29, but i will submit for this event to see what do you guys think about it.

My entry will be a 2D HTML5 Game engine which can be used with the Dart language.  It’s name is DartRocket and you can already found it on github and on Pub(Dart package manager).  My plan is to make it a more usable during Tool Jam and I hope I can show that Dart is capable of making HTML5 games.