Also free for Android, Kings Kollege's Hivex is a simple puzzle game where your goal is to light up all the hexagons in each level. Clicking on one lights up all its adjacent neighbours, while if you click on a tile that's already lit (or a have one adjacent to the unlit one you're clicking), it's light will go out, and the number of clicks it takes you to get everything shining brightly influences your star rating at the end of the level. Later on, some hexagons are only able to be toggled a certain number of times, while others can't be turned off or on at all, and a few other rules added in keep you thinking. Cap it all off with some silky smooth animation, bright colours, and a funky yet relaxing soundtrack, and you have the sort of puzzle game that's perfect for passing the time. Hivex is the sort of thoughtful, well put together puzzle game players looking for something casual but smart will appreciate, no bells and whistles required.
Android:
WTF is the level 3 set only available on mobil, when its free there anyway? (I could understand if they asked you to buy it for the next set, but so... )
What a simple, relaxing game this is! True, some of the later levels can get a bit frustrating, but the lovely graphics, the seamless animations, and the gentle music help to make this game an enjoyable way to spend (or waste) some time.
Update