Pretty fun game.
The game bugged when I tried to replay after losing the first time so I refreshed the page.
After that, the enemy AI seems to have broken because they stopped moving. I got up to 20 merch before I stopped.
The enemy death animation seems to cause a lag spike. I suggest having the animation ready but hidden and reusing it each time an enemy is defeated as opposed to instantiating a new one each time.
Also, setting a goal would be nice too. For example, if you collect 10 merch you get an ending with a happy Marine.
Overall a nice entry.