Eternia is made in the BYOND engine, which is both an easy-to-use gaming engine and a vibrant community. You can play Eternia by simply downloading and running the client, and making a BYOND account.
Unfortunately, we don't have support for Mac users as of yet but this should be a possibility in the near future. The developers at BYOND are working on Flash support, which will allow for any internet and Flash-capable device to play Eternia.
• Any Windows machine
• Stable and fast internet connection
• 100 MB of RAM
• CPU clock speed of 1 GHz.