Good game, common oversight
This game utilizes a clever game mechanic: eliminate all the blocks without causing any of them to move too drastically. A pair of cards show you which colors you can eliminate, introducing the challenge: you can't just work from the top down because the color cards may require you to remove a block that is smack in the middle of a cluster.
Overall it's a decent puzzle game, but it does suffer from one major setback that I see way too often in games of this sort: color choice. I'm colorblind (not the nasty black-and-white kind, the sometimes-you-get-colors-confused kind), and the bright yellow and greens chosen to represent two of the blocks are so close together to me that I can't tell them apart, even when they're literally right next to each other.
Colorblindness isn't an uncommon problem. It's so common, in fact, that major video games like Halo and Call of Duty offer secondary color schemes that are colorblind-friendly to ensure that you can tell who is and isn't on your team, and puzzle games often use shapes in tandem with colors to enable the player to better distinguish between them.
When in doubt, use the following rules: use starkly contrasting colors on the opposite sides of the color wheel as much as possible-this means this game should probably have used red, yellow, and blue. If you must use adjacent colors (yellow and green, for example) separate them from each other by using a medium or dark variant of the color (dark green is easy to distinguish from bright yellow). Colorblind people have trouble telling apart mixed hues (blue and purple, red and orange, yellow and green), so alter their value (lightness) to make them more distict.
Otherwise, great game, good work!