Jacks or Better Double Up is a popular video poker variant developed by NetEnt, based on the classic Jacks or Better game. Players aim to form a winning five-card poker hand, with a pair of Jacks being the minimum qualifying hand for a payout. After any winning hand, players have the option to engage in the 'Double Up' gamble feature, allowing them to risk their winnings to potentially double them by choosing a higher card than the dealer. This blend of strategy and risk makes for an engaging poker experience.