Arm wrestling is a new feature in the game and it is also the best money maker of the three primary mini-games, once you master it. Once you've entered an arm wrestling match, you'll be presented with a long gray bar, a shorter orange bar, and a circled cursor on top of it. The point of the game is to keep the cursor inside the orange bar. As the time progresses, the orange bar gets smaller and Geralt grows tired. If you manage to keep the cursor inside and the orange bar reaches the right side, you win. The orange bar automatically moves to the right, but will shift to the left (your opponent's side) if the cursor exits its perimeter for even a minute period of time.
Bets in arm wrestling seem to be higher than in the other mini-games, and you earn double the reward (for the time being, anyway). For example, if you bet 30 orens, you'll receive 60 orens without the game ever taking away your original 30 orens from betting. We're betting this is a bug, but, hey, it's a 200% profit so we're not complaining.
The main idea of dice poker has remained intact in The Witcher 2, but the execution of the game is slightly different. As usual in a poker game, the combinations from strongest to weakest are: 5 of a Kind > 4 of a Kind > Full House (Three of a Kind + Two of a Kind) > Six High Straight (2, 3, 4, 5, 6) > Five High Straight (1, 2, 3, 4, 5) > Three of a Kind > Two Pair > Two of a Kind > Single.
Once the poker game begins, you'll be in a mode to throw the dice. Make sure not to shake your mouse too much or the dice will fly away from the board, resulting in reduced dice for you for the remainder of the game (you can still win, but it's obviously much tougher). Dropping the dice without shaking works just fine as well, so a cautious approach might be a good choice in a critical game. The camera has changed from a top-down view to an angled isometric sort of view in the sequel, which tends to make the throwing action somewhat harder. As far as winning goes, it's all about luck.
The amount of games to win for the sake of the dice poker quests has been changed to one instead of two. Also, the betting system is very low, making dice poker in the sequel a very inefficient way to earn money. You can initially bet 5 to 10 orens, with an additional bet from your opponent in the same range, and then you can bet again once you're ready to throw the dice for a second time. Overall, the total profit you can earn is limited to approximately 20-30 orens.
Fist fights have also been drastically changed from the first game. The whole execution consists of various QTE combinations that utilize your directional keys (W, A, S, D). QTEs which appear will either be a single key press, after which Geralt will deliver a successful blow (if you pressed the right key in time), or they will be linked into two consecutive key presses (for example, "W" and then "A" almost immediately afterward) after which Geralt will deliver the hit.
Enemies usually have way less health than you do, but that doesn't mean you should let yourself get hit. In fact, you can get away from every fist fight in the game without getting a scratch, as the "game" tends to be very easy once you get the hang of it.
Winnings from fist fights aren't exactly that high, but it's better and less luck-dependent than dice poker, which makes it a viable option if you're looking to knock a few heads around.