Osu - Osu is Music, Rhythm, Single and Multiplayer video game developed by Dean Herbert.
Slack - A messaging app for teams who see through the Earth!
Clone Hero - Clone Hero is a free rhythm game, which can be played with any 5 or 6 button guitar controller...
Mattermost - Mattermost is an open source alternative to Slack.
StepMania - Rhythm game for Windows, Mac, and Linux.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.