Enjoy a trio of minimalist puzzlers for free, as Klocki, Hook, and oO go on sale

Rainbow Train Games has been releasing slick minimalist games on two years, from oO to the recent Gold Award-winning Klocki. Now, you can play their three games for free on the App Store.

oO is an fast-paced arcade game, set through stages of connected rings (hence the clever title). Spikes and rotating circles challenge you to swap between exterior and interior of the circles to dodge hazards and survive till the end.

Hook tasks you with untangling a network of intertwined poles, activating circuits to retract the poles without any collisions. It's a relaxing subdued puzzler, that explores its simple mechanics in interesting ways.

Klocki plays like an evolution of Hook, featuring three-dimensional stages and clusters of lines that you to rotate and connect. From switches that alter the level to special tiles, Klocki has a varied array of different mechanics to learn.

You can download oO, Hook, and Klocki on iPad and iPhone.