Ground Effect is being developed alongside a cross-platform library. This means that there's also a fully functional PC version.

The PC version also has the map and level editors built in

As a result, it's possible to switch between editing and playing a level on a single keypress!

It also allows the use of Microsoft's debugger which is, from the developer's perspective, a hell of a lot easier to use than the one in XCode. (It is of course entirely possible that his opinion is skewed by well over a decade of experience with MSVC/Dev Studio...)
Many thanks to Andrew Cakebread at Massivehadron for his programming assistance, to Andy Robson and his team at Testology for their game-testing expertise, to Tartan Monkey for his graphics and to Mikey and Jack Corpes, for their contributions to level design and graphics.