Reiner Knizia is a designer extraordinaire of board games, many of which have already found their way onto iOS, including the excellent Samurai. But in recent years Knizia's work has been finding its way onto iOS less as conversions, and more as platform-specific new games.
Roto is another of these: a singleplayer puzzle game with simple rules. Six wheels, each containing six coloured slices, are arranged around a seventh and central wheel. You rotate these wheels clockwise or anti-clockwise one slice at a time, attempting to match up the colours in certain configurations. Roto's central idea echoes nothing so much as Bejeweled Twist, and on a basic level it comes down to teasing the circles into a flurry of match-three points-scoring. But its system, and the ways it can be played with, make Roto's real currency the wasted moves – for which points are removed. The hidden danger in every stage is leaving yourself lots of slices with no way of matching them, and without careful planning it's a frequent outcome.
Across several modes Roto changes the conditions. In Puzzle mode the challenge is working out the right sequence of moves for a board where matched slices disappear, while in Arcade mode the focus is on matching as quickly and efficiently as possible, as colours slot back in and open up new combos. Action plays out similarly to Arcade, but by putting a time limit of one minute on top of things, Roto becomes almost panicking, and as far away in feel from the Puzzle mode as it's possible to be.
Roto's reserved visual design turns out to be exactly the right choice for what its most pressured play demands, the colours and possibilities always clear, and the sparse audio effects never distract from its first purpose as a brain teaser. But next to certain of Knizia's previous games, the likes of Topas and Money, the overall effect is of elegance without ever quite rising to brilliance – it's a simple, well-executed concept that never threatens more. Roto is austere and cerebral, an involved challenge that has to be respected for the intricacy of its design, but is hard to love for it.