Decent concept for a game, but a few suggestions.
ASWD support - a lot of gamers are used to useing ASWD instead of arrows, would be a good idea to consider putting adding it.
Skip button - It takes 12 seconds to die, 12 seconds for the title screen to finish loading, then 21 seconds to go from the opening animation to gameplay. That's too long of a turnaround time to try your next round, it would be helpful to either have a skip button or a try again after death, and it might also be a good idea to shorten the time for how long it takes for you to die. It feels too punishing and would cause a person to just stop playing.
Monster Doors - I know it's a punishment but some feedback that makes it feel like you are either fighting off the monster or getting away from it so it doesn't feel like you are just waiting out getting hit
Door fade in - you may want to either have the doors fade in a little faster, or have the timer start ticking a little later, felt like by the time the doors were there I had a split second to decide.
The music and art were great though, and I like the animations and the doors. Even though the intro was really long, it did a good job to set the mood, which is why I'd say a skip button after the first run would be nice. You might also want to consider if there could be a little more gameplay for the player since it's basically a guess the door game that doesn't seem to give you any hint on which door to avoid.
I can tell you put some real effort into this, just needs a little more to it gameplay wise.