That will be free for the entire month of April, according to an announcement from Microsoft.
Each month, anyone with an active Xbox Live Gold subscription can claim up to four games that will all work with their Xbox One. Xbox One owners will be treated to Assassin's Creed: Syndicate and The Witness while 360 owners will be given Cars 2 and Dead Space 2 to keep.
The Witness is designer Jonathan Blow's followup to his debut indie platforming hit Braid. The game focuses on puzzle solving, delivering a Myst-like experience as players explore a mysterious island that is crammed full of interesting and unique puzzles. Starting on April 16, it'll be joined by Assassin's Creed Syndicate, the 2015 entry in the AC series that's set in 19th century London.
With many of these offers going live on April 1, you still have a few days left to grab the free games for March, so be sure to do that if you haven't already.
Games with Gold first launched in the summer of 2013, offering free games every month to those with an Xbox Live Gold subscription, which costs $10 a month or $60 annually. As survival horror games go, the Dead Space franchise is fondly remembered, though if you've never played it before, it might be worth trying to pick up a copy of the first game on the cheap before you dive into Dead Space 2. As usual, both Xbox 360 titles will also work on the Xbox One thanks to the console's backward-compatibility feature. You never know when you might need it.