Nice job on your first entry! I think 5 minutes was a little too long, but I enjoyed traveling the maze and trying to find more energy. The controls felt great, and I liked the art for the ghost. I was able to get the good ending. :) 

It's a simple and fun mechanic but the enemies and the time doesn't make a challenge to survive, making the game monotonous.

The game applies well the wildcard and the graphics are fluid.

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.

Clean and simple game, at first I thought it was so easy but towards the end I finally died. I think it wouldn't be so hard to implement the wildcard of difficulty levels, like speeding up the enemies, the rate of the bar etc.

Good work!

Cute game. Be great if you can stop the character going offscreen.