Questions regarding old copyright

[jettclass]

Hello, so I have a question about copyright on a 10 year old game.
Stubbs the Zombie is a video game released(or made in)
2005 realeased for XBOX, MAC and PC. It is currently discontinued on Steam and sale stores everywhere, of course, since no one uses an xbox original (I still have one.) So Let's get to the real question here.

Stubbs the Zombie, would it be illegal or legal to download and play on your computer, since it is
discontinued from sales, even on steam even though it WAS available earlier in its initial release. It's a 10 year old game, and no one even remembers the game, and I doubt even the creators remember making this amazing video game. So, before I try to play it, I want to ask if it would be illegal to download it.

I love this video game and I still even have the demo disc that comes with a call of duty demo as well as gamer news and etc. It was fun and is still is fun and would love to play it again. Thanks for the answers!

P.S. I'm sorry but i don't know where to put this at, so i put it here just in case. Thanks!