Add: Rhythm Game Software

[MatthijsMarco]

Guitar Hero and Rock Band revival projects:

• Clone Hero: Freeware, but proprietary.
• Frets on Fire X (fofix): Open Source, but less popular and potentially outdated/unsupported.

DDR revival project:

• StepMania
• Etterna: Fork of the former. Claims a focus on keyboard players.

All of the above, and karaoke:

• Performous

[lpchaim]

I'd say osu would fit nicely as well, unless the mouse focus makes it a no-go

[Lazorne]

I will add these as separate issues instead

[Lazorne]

I'm closing this down as we track them separate