Short but cool proof of concept. I'd replace squares by something more meaningful, like people, or animals (like sales employees making money, or chickens making eggs). Also bosses tend to break the game, I think you can stretch it out a bit if you nerf bosses and add like 2 more upgrades between the boss and the black hole.

Other than that, I liked it, needs polish of course (prestige, achievements, challenges, better graphics) but it's a solid base to start.