If you have never heard of Bullet Run before now you wouldn't be the only one. The free-to-play MMO did not receive much media attention when it launched and only saw a handful of reviews. Reviewers didn't much care for the property and it seems gamers didn't as well. Although the game only launched last August, it is being shut down next month.
Sony Online Entertainment published the game to expand their MMO catalog, but perhaps they should have shopped around longer. Acony Games certainly tried to create something great, but there are so many F2P options available these days that it's hard to stand out. Bullet Run is a simple MMO shooter which didn't have a chance in the current landscape.
Those with any "Station Cash" in the game will not be refunded. Instead, the money will be saved to your SOE account to be used with other games. Beyond that, those who subscribed will see their subscriptions terminated this month and receive prorated refunds. It's always sad to see games end, but with so many vying for users it must be expected that many will fail.