XCOM 2: War of the Chosen
The original XCOM: UFO Defense was a seminal video game, and its brand of squad-based tactical gameplay coupled with its strategic layer was incredibly novel upon its launch in 1994.
When Firaxis rebooted the series in 2012, they kept that same winning formula and modernized it, and XCOM 2: War of the Chosen is the latest and best example of this evolution.
By taking a page from the Middle Earth games’ much-lauded Nemesis System, there are now elite aliens that can be encountered to further randomize gameplay and constantly keep you on your toes.
In addition, The Lost is a species of zombie-like creatures that can spawn under certain conditions and will attack both your soldiers and the opposing alien forces, to really mix things up.
Along with hero characters that can join your campaign, and a terrorist faction that can further make your life difficult, War of the Chosen allows near limitless replayability.