Yeah, spawning one more enemy is used to show as the element for the theme "+1". While Spawning the enemy the position of spawning is at a lower height which allows the box colliders of the enemy to move into the floors box collider and some enemies tend to move inside the floor.
I will start working on the score system from tomorrow, and will fix the buggy ending.
There is also a bug, when an enemy touches you. You're health will be reduced by one point but if it sticks there for longer it won't hurt you anymore.
I am planning to fix these bugs and give the player a goal or ending which makes sense.
I am thinking to expand the game and work on it, so it may actually turn out to be a game.