Unity is probably the most popular tool for cross-platform development out there right now -- last week at GDC, I heard a lot from developers of all sizes about Unity and how it was helping them to build games for iOS and other platforms. But Corona also has a following out there. It's a Software Development Kit (SDK) that has been updated quite a bit lately, and I did hear a few devs say it's what they use to make their titles. One game development student even told me he's being taught how to use Corona specifically at school, so the tool definitely has its fans.
Today, Corona has announced that it's hoping to make its platform more accessible than ever, with