So when I play The Forsaken Lab 3D I was on level 5 and the game keeps spawning zombies 
Is it the one with the huge zombie in the sewers? Its a very hard level even for me; the only way I got through it was to go to the area with the beds, grab the key or door unlock interval, and run straight to the next door by spamming water canteens.
You may have to kill some enemies but this is the only level were rushing is the best option.
well im stuck in level 2 that i can’t go downstairs because it makes an invisible barrier that it won’t let me go to check if there is a button or a key or some food or ammo i don’t know what’s downstairs actually.