The file is in "iCalendar" format (.ics file), and will import into a Google calendar.
This has successfully imported into my Google calendar which then synchronised with, and updated, my computer and phone. You may possibly need to modify the format to import it into other calendars.
To import the Aikido Calendar into a Google account...
- Save the file to your computer, using the link at the bottom. Depending on your operating system, you may be asked to select a format for the download - use page source. Also, be careful not to accidentally edit the file.
- Log into your Google account and bring up your calendar.
- Click the + sign next to Other calendars.
- Select Import.
- Click Select file from your computer, and find the Aikido Calendar file on your computer.
- In the Add to calendar box, select the Google Calendar into which you'd like to import events, then click Import.