Free Play Days is where Microsoft picks a handful of games for Xbox Live Gold/Ultimate Members to try out, free of charge, from Thursday until Midnight Sunday. We tend to get a decent little mix of games to try, with these games also sometimes being on sale too. So if you want to keep the game after enjoying this free play you can at a lower price than normal. Achievements also unlock when trying these games out over the free play period.
The xbox store link to the games now available for this weekend are as follows.
On sale for £9.99/$11.99, but is also part of Xbox Game Pass.
The Silent Hill edition is also on sale for £35.99/$39.99 if you have Xbox Game Pass Ultimate.
Doesn't appear to be on sale as it's still a whopping £59.99 if you want to keep it after this free play.
Also part of the Xbox Game Pass catalogue, but on sale for £3.74/$4.99 if you do not have Game Pass.