Great use of the limitation. The incremental accumulation of weight felt rather natural.
In practice, I was usually moving around with 2 weights--that seemed to be the sweet spot in terms of allowing me mobility without requiring an extravagant number of trips.
The sound effects were a bit too loud, especially when the player character is damaged.
One small suggestion: The controls in the Description should reference Up (to pick up a weight) and Down (to drop a weight). While the tutorial does include arrows to demonstrate these functions, I would suggest that if you are listing the controls in the Description, that list should be complete.
Also, since you haven't enabled Full Screen, the Space key shouldn't be used for jumping--that just scrolls the browser. I was using the J key, which worked just fine; I would suggest that the tutorial display the J key (or one of the other alternatives), or else you could enable Full Screen.
