Even though it came out for PCs years ago, it is my (darkhorse) pick for GotY! Don't think; just buy! I PM'd it at the $30 mark. But be forewarned: it's heavy heavy heavy puzzles. Solve a puzzle, read a lot of text, rinse and repeat. If you didn't like Portal, then stay away from this one...
http://www.walmart.com/ip/Assassin-s-Creed-Unity-PS4-Pre-Owned/42640096
Here's the XBone version: http://www.walmart.com/ip/Assassin-s-Creed-Unity-Xbox-One-Pre-Owned/42640099 Not as big a discount. For 43 cents more you can buy a new copy.
I know. I went to bite and they were all gone! It's back now but they raised the price to $14.99: https://www.gamefly.com/#!/game/Assassin%2527s-Creed-Chronicles/5010037
I've been eyeing this and the price keeps fluctuating (dependant upon the seller). I paid $11.91 but now it's up to $12.13. Get it while it's cheap: https://www.amazon.com/Assassins-Creed-Chronicles-UbiSoft/dp/B0194I5PVW/ref=sr_1_1?ie=UTF8&qid=1465854321&sr=8-1&keywords=assassin%27s+creed+chronicles