While we do not officially update BitGym on the Fire app store, we have seen that you can "side load" BitGym onto your Fire TV, Fire Stick or Fire cube.
Install the app from your Android phone using Apps2Fire
1. Go to the Fire TV home page, then navigate all the way to the Settings tab on the far right. Highlight “Device,” then “Developer Options.”
2. Highlight “Apps from Unknown Sources,” then press the center button. Select “Turn on” on the warning screen.
3. Turn on ADB Debugging
4. Turn on USB Debugging
5. From your Android phone, install BitGym.
6. From your Android phone, install Apps2Fire and follow instructions to install BitGym on your Fire TV.
Install directly from APK (if you don't have an Android phone)
1. Go to the Fire TV home page, then navigate all the way to the Settings tab on the far right. Highlight “Device,” then “Developer Options.”
2. Highlight “Apps from Unknown Sources,” then press the center button. Select “Turn on” on the warning screen.
3. Go back through the Settings menu until you get to the Fire TV home page. Then, using either the Search tool on the far left or the Alexa voice search button on your remote, search for “Downloader.”
4. Use the Downloader app to enter a URL for a BitGym APK. You can find the most recent BitGym APK links on this page.
If you need more help, HowToGeek has a comprehensive guide on side loading apps onto Fire TV.
Note: BitGym is available in the Google TV App Store. Learn more.