This is one of the hardest puzzle games I've played on this site. At the start it's quite easy, since you will need to get used to the controls and the way of playing, but later on it gets really hard.
But it's not just the puzzling element that makes it hard, also a small frustrating way of programming. What I mean, is that you can't choose which way the roboblox link. Especially on the later levels, like level 19, very often I place them in a way that the roboblox could clear half of the field, but instead one or two blox link to a blox outside of the area I want to clear. If you could choose which blox you would like to link to, it would make the game a lot less frustrating, and a bit more fair.
Some levels require way too long IMO. It might just be me having a bad strategy, but I spent half an hour on level 18 gaining and destroying loads of blox with three links, until I finally got enough blox with 1 and 2 links to close off all the links.
Other than those things, it's a great game. It's extremely challenging, which is fun sometimes. The graphics are fine, and there are enough levels. I really wish you'd change the first thing I mentioned though. Maybe you can let us select which way to link with the arrow keys?