You have a real nice base for a full game here, everything's very polished, it's satisfying to place down gears, and I think the idea could be expanded pretty far. However, I did think the levels were way too easy; there was practically no thinking involved in most of them, and when there was, it was mainly because of the darkness, so it feels a bit like artificial difficulty. If you want to expand this idea further, there's a lot of interesting mechanics that come to mind when I think of cogwheels: different gear ratios, chain drives, using them to activate mechanisms, etc. Well, I don't make puzzles, so I don't know how you'd go about implementing these ideas, I'm just sharing my inspiration. Anyways, good job!
Also, I was really missing restart and undo buttons. But maybe Baba Is You spoiled me too much.