A few days ago the multi-platform Unity engine had a brand new update (version 2.6) as well as a price drop for independent developers who choose to use the engine for both personal and commercial use from $200 USD to well zero.
David_Helgason_CEO_Unity_Technologies wrote: With the explosive growth in new platforms and performance improvement in our Unity suite of products, we believe that there are no technical hurdles remaining for high quality interactive content everywhere. Now we are removing financial hurdles as well. Unity is mature enough and easy enough to use that it can be the entry point for those developers taking their first steps with the technology.
Now I can hear your eyebrows raising but before you ask there really isn't any catch to this, aside from the Unity spashscreen that is. So there really is no reason as to why your not tooling around in it as you read this go and download it now!