i won from another giveaway site... a game...

There's another giveaway site? O:

install steam enhanced, open that page and you should see if you have that game in your library

It's fine & it's the full game. You'll usually see the 'beta' during the activation when the key comes directly from a developer. Keys that are meant for streamers/youtubers/etc but dev has some left over.

Also, your ratio is outta control!

I think it had -50% off a few weeks ago.
I remember almost picking it up but staying away because of the mixed reviews.
"Beta" activation usually just means it's an Early Access title, but is still the full game.