Far Cry Instincts and Far Cry Instincts: Evolution are video games in the Far Cry/Assassin's Creed/Watch_Dogs universe
In Watch_Dogs we see arcade cabinets bearing the name of Far Cry 3: Blood Dragon, meaning it is a Game Within a Game, presumably developed by Abstergo Entertainment, who appear to be the in-universe equivalent of Ubisoft. It still bears a "3" in the title, though, meaning there must be two other games before it. What are the other two irregular games in the Far Cry franchise? Instincts and Evolution. Instincts would likely be Very Loosely Based on a True Story (The actual, in-universe events of Far Cry), and Abstergo would just be using the games to cover what really happened (Since they were probably involved with it anyway), similar to what the did with the in-universe release of Assassin's Creed III: Liberation.- It should also be noted that, much like what Abstergo's treatment of the Assassins shown in Assassin's Creed IV: Black Flag, Instincts portrays the protagonists in a much harsher light than the main game.
This game and its successors are set in the Falloutverse
The Trigen serum is a precursor to FEV They behave like Vault 87 and Institute Supermutants. Also, Far Cry 5 ends with a nuclear Armageddon. Need I say more?