In Buzzled, every hexagon space is either yellow or black. Each has a number. Each row has a sum of some of those numbers, coloured yellow or black. You have to work out which hexagons should be yellow (or black) to lead to the correct sum.
So, for example, on the bottom-left row here, you can see that only one of the 1s can be coloured yellow, and anything greater than a 1 should be black. The 5 on the far right side must be black, since that column has a maximum sum of 4 in yellow. The top-left row, not yet filled in in this screenshot, can only be configured in one way, with the 2 being yellow and all others being black.
It’s similar to picross in a way, but with a different labelling convention and a need for more complex sums.
This screenshot is of the ‘expert’ level; I completed it in 9 minutes 17 seconds. There’s also a ‘mini’ and a ‘classic’ mode, with smaller grids. And there’s a ‘master’ mode, where you are instead just told the number of hexagons that need to be a certain colour. I’ve not quite worked out the maths behind that one yet.
You can play Buzzled at https://puzzmallow.com/buzzled – and you can try Collections and Quickflip while you’re there.