Here, use wine to play it on Linux, but it may not be perfect.
https://github.com/ShadowDumb/FalloutEquestriaRemainsLinux/releases
You can also use Standalone Flash Player to play this game.
1. Download the zip version of this game here, download "pfe v1.0.1.zip".
2. Download Standalone Flash Player here.
3. Unzip the game, run "pfe.swf" through Standalone Flash Player.
PS: If you find graphic errors when playing this game with Standalone Flash Player and Nvidia Prime Driver, then you have 2 ways to solve this.
1. Don't use Nvidia Prime Driver, use Bumblebee, or anything else, just don't set your Nvidia card as a main graphic output card.
2. Download the Windows version of Standalone Flash Player, run it on wine then play this game.