I had to go up and down a bit every so often to keep the camera centered, it does not quite follow the movement speed. I also though the same as MikeCodev about speeding up the enemies through difficulty levels, and maybe removing some or making the health items give less health.
The game itself was pretty fun! I relaxed a little when I found a room with health and saw that the enemies didn't go through walls, until some of them did and I had to get out. The map is big enough to keep running for 5 minutes. At first I though there was too much health items, but at times I almost ran out, so it is kind of balanced.
The only thing I would add besides the difficulty levels is some kind of pathing for the enemies to surround the player. I think now they just follow your position, so with that in mind I could win by going through the perimeter of the map and letting them follow me.