The connection to Hook is immediately apparent as soon as klocki boots up: it's a no frills, no story, no nonsense puzzle game that's all about exercising your wits for around an hour. Unlike Hook however, you likely won't walk away from it thinking "was that really it?" I enjoyed Hook but couldn't really say it hooked me; klocki on the other hand, kept me enthused all the way to the end.
The biggest difference between the two games (besides the bright colors) is that klocki changes up how you interact with it. It's primarily a game about moving squares around so that they form either complete circuits or rounded-off line segments, but the mechanics will be shaken up every five levels or so. At first you'll patching together simple circuits, then you'll be creating circuits on three dimensional objects, then the way in which you can spatially manipulate the tiles will change, then you'll be making multiple circuits, etc. It starts off extremely simple but gets visually complicated, to the point that outsiders will likely be unable to parse any information at the final puzzles.
Like I mentioned, what keeps klocki ticking is that any time you get bored or frustrated with a mechanic, the game will quickly shift over to something else. The only time I'd argue that it gets particularly vexing is when sliding blocks are introduced, since the rigidness of that mechanic doesn't flow with the laid-back pace of the rest of the game. Thankfully the three 9x9 stint of sliding puzzles is the worst of it; for the most part, klocki is a relaxing game to mellow yourself out with at the end of a long day. Like Hook it's not a brain burner in any way shape or form, but it'll still provide a gentle release seeing your lines light up.