We haven't exactly been overburdened with touch-based Windows 8 music-making apps, but the market has just got some heavy-hitting support from Image-Line with the release of FL Studio Groove.
Designed for both production and live performance, this features a 10-pad sample-based drum machine and five polyphonic synth channels. There's a piano roll, mixer and effects, and you can create both loops and complete songs. Most parameters can be automated.
You can get an overview of FL Studio Groove in the video above or watch a getting started tutorial below. The app runs on Windows 8 and Windows 8 RT compatible devices (x86, x64, ARM processors) and is currently available for the discounted price of $4.99 on the Windows App Store. This price will rise to $11.99 at the start of October.