Maelstrom
Classic arcade game where you navigate through space, zapping asteroids before they destroy your ship.
Older free apps
Noto
General-purpose text editor supports extensive encoding, multi-selection indentation, invisible characters and iCloud Drive integration.
Gifski
Convert videos to high-quality GIFs.
DeskCover
Deal with a messy desktop by highlighting the active window and covering the clutter on the desktop. Colours, wallpaper and pictures can be customized.
Left
Distraction-free editor allows you to place markers in your text, which show up in a side panel. Comes with an inline thesaurus.
Tomahawk
Open source music player without the iTunes bloat allows you to gather all your music sources and downloads in one place. Create playlists, invite friends, listen to radio stations.
Manta
Customizable templates for creating invoices and keeping track of them. Contacts allow you to keep information for billing the same client. Save as a PDF, then send it by email or print it off.
Padlock
Open source app for storing passwords, serial numbers and other sensitive data — protected with one password. Available on all major platforms, with syncing between them.
Akaunting
Accounting software for small businesses to manage finances and cash flow. Takes care of invoicing, accepting online payments and keeping track of expenses. Can be installed on your host/server.
Windowed
Stripped down mobile browser allows you to upload photos to Instragram directly from your Mac desktop.