DiRT Showdown can be downloaded for free through the Humble Store and is available right now until Saturday, Jan. 14.
The 2012 racing game must be redeemed through Steam by 10 am PT/1 pm ET on Saturday, Jan. 28, and works on PC, Mac, and Linux. The free offer also comes with a 10% off coupon for the Humble Monthly, a monthly subscription of curated games for a flat fee of $12. The current Humble Monthly offers XCOM 2 to download and play immediately once subscribed.
The Humble Store has given away other Codemasters games in the past, such as DiRT 3: Complete Edition and GRID. The two games have since been delisted from Steam and other digital marketplaces at the beginning of 2017.
The reason for delisting a game is possibly due to expiring licenses since the games use fully-modeled cars by real manufacturers. A game can no longer be sold once delisted, but anyone who owns it can still re-download and play. DiRT Showdown is still available on digital storefronts for $14.99.