A decently simple concept of a game that, in general, is executed fairly well.
I think the idea, over all, has merit, but there’s a few things keeping this from being a game, in my opinion.
First, there’s no built in challenge. Just spam boxes. This can be cathartic in it’s own right, but perhaps if the player was given a limited number of boxes they could spawn, or if there was a time limit to reaching the top… as it is, I’m kinda just clicking.
Second, the game, as it is right now, can be “beaten” in 4 mouse clicks. When a level starts, I just need to scroll to the very top of the screen, move my cursor so I would spawn a box just past the top edge of the level, and I win. I don’t actually have to stack anything.
Personally, I think just a simple level timer and a check to see if a spawned box is colliding with another box at the top of the screen (forcing the player to stack their boxes) would elevate this to a game.