After upgrading my Mac to MacOSX 10.10 Yosemite Delta2D does not work any more. What can I do?

Before Mac OS X 10.10 Yosemite, Java was distributed by Apple via the App Store. Yosemite comes completely whithout Java. If you request for java the Mac OS way, now the most recent version of Java will be installed. As for now (11.2014) this is Java 8.

In order to work, Delta2D 4.5 and older requires Java 6, which was also included in Java for OS X 2013-005, the last version Apple issued.

So please download Java 6 for Yosemite, install it, and Delta2D will work again.

[UPDATE 09/15/2015] Beginning with Delta2D 4.6 Java is included in the Delta2D package and not required to be installed in Mac OS X any more. Anyhow, Delta2D's Java does not conflict in any way with any Java version installed on your Mac system.