Giveaway!

I don't think you will get any entries.
As far as I know the game was in neither in a bundle, nor on a high discount, so most people here will not own it.
Those who really wanted the game, bought it before the bundle that contained the OST, so they probably have the OST from the bundle.
I assume, you will only get entries for this OST after the base game was in a bundle.

For the future, if you want to have higher chances to get some participants, I'd suggest you to let the giveaway run longer than a single day, as not everyone checks in here daily. (Max duration possibile is 30 days, in case you don't know)
Good luck though :)

The key is really old, so i'm not sure if it still works. Will delete giveaway if it does not.

You cannot simply delete the giveaway if the key doesn't work. You'll need approval from the winner and ask support for deletion. Maybe you should change that text to something like: "I would really appreciate if you let me delete the giveaway if the key doesn't work."