The Arcade DLC Add-on for Tumblestone has 6 achievements worth 500 gamerscore.
Get a score of 333 in Heartbeat.
Empty the board in Heartbeat.
Get a score of 500 in Infinipuzzle.
Get a score of 333 in Infinipuzzle using a modifier.
Get a score of 1,234 in Marathon.
Empty the board in Marathon.