升级免费版, also known as "Upgrade," is a popular four-player poker game in China. Players have the option to play with one deck or two decks of cards. When playing with one deck, it is referred to as "40 points" or "打百分." When playing with two decks, it is known as "80 points" or "拖拉机."

Similar to the game of "Upgrade," the gameplay involves four players competing in pairs to earn points. The basic rules are similar, with the addition of more cards (from 54 to 108) and the removal of restrictions on scoring from the bottom cards in the "拖拉机" variation. The game introduces new card combinations such as "对牌" and "拖拉机" (which is where the game gets its name) and additional rules like "双抠翻倍" to add more entertainment and excitement to the gameplay.

升级免费版 is a free game available on the iPhone platform. It offers a concise and competitive gaming experience for players who enjoy four-player poker games.