Duet ($2.99) from Kumobius rates as one of the best of the bunch of minimalist, challenging, arcade-style games. And now the Australian developer has made the game free for a limited time in honor of Australia Day. You play as a pair of orbs that spin around a central point, and must try to make it to the end of a level without hitting anything. There’s also endless modes and daily challenges to take on for high scores. Those were added as post-release updates, along with new music and a narrator, to add some flourish to the game.

This is the first time that the game has gone free on the App Store, though it has been free at Starbucks before. While the latest “Epilogue" update indicates that the game may be done with major content updates – and Bean Dreams ($2.99) is the current focus for Kumobius – there’s still so much to take on here. And for free, it’s hard to go wrong for what really is one of the best games of its kind. Pick this one up while you can, as it may go back to paid really soon, once Australia Day ends. So hurry up and grab it now if you haven’t already!