This game is set to the optional 'Ironman' mode, so the 'Solve' button is not available. WE need to remove squares from the ends of the rows in groups of three. Where to start? It must be three purple squares, but there are four to choose from.
We clearly need to unlock three green squares for next turn, and we will need a third red if we are to get anywhere. Hmmm... I picked a tricky one for this diagram and I'm not sure of the answer! I think probably the two ends of the top row, and the right side of the bottom one, aiming to get at all six purples that are close to the edge.
If you can remove all of one colour without affecting anything else, it can't be bad! Just left-click to select or unselect squares, right-click or space-key to remove a group.
The counters at the top say how many of each colour are left. In the full version this is more useful because they don't always come in threes. If you have set groups between three and four, and there are ten reds left (for example) you know that you must remove one group of four and two groups of three reds - in what order is up to you!
Other features include all the usuals - select your own colours, graphics auto-size to match window, position saved automatically when you quit, background music...