Actually quite enjoyed this. Great atmosphere and love how the music gets faster when being chased by the monster. Had to rearrange all the gems at the end as I blocked the doorway to escape. The lighting effects were also brilliant and is really well made to say it was done in a few days.
A few additional ideas from me would be that it might be worth mentioning how many gems are left to find. Though that is just an opinion for a personal preference as towards the end I wasn't sure if I was doing something wrong.
Also, after completing the game it seemed that the options "escape for Real" and "retry" didnt work. Again, I could have been doing something wrong so maybe it is actually fine.
Ah also, love the monster design :).
Well done.