The Anniversary Update for puzzle game Pictopix [Steam] is a good one, adding in plenty of new goodies to keep you going.
It's no small update either, it adds in 45 new puzzles some of which are rather large, new achievements, new secrets and zoom button for big grids. That's quite a content update, considering the developer release it for free I'm pretty impressed when a lot of other developers cram DLC down your throat.
It also has a shiny new trailer:
I actually tested the game back in February of last year, where I came away pretty impressed with it. So I'm pretty pleased to see support for it has continued into this year!
The developer said they're also willing to get the game on GOG, they suggested voting for it here if you wish to see it. Otherwise, you can find it for £4.99 on Steam which is a great price for so much content.