Endless flyer Race the Sun is free today for PC, Mac and Linux on Steam.
This is in honour of developer Flippfly releasing the iOS version of its ambient score-chasing arcade game. You can snag that for £3.99 / $4.99.
Race the Sun also just received its Sunrise DLC. "This beautiful new mode has all the speed of the original but without a setting sun, an increasing difficulty, or a leaderboard," Flippfly noted on Steam. "Just settle in and zone out for one infinite region of bliss."
The developer also added a recent update that adds a first-person cockpit view and the option to see your friends' high scores.