Something I love about video games is that when one does well, it usually means that a sequel will happen sooner or later, and unlike movie sequels video game sequels usually add new stuff with each new game. Knights of the Old Republic 2 has a ton of abilities, and character character profiles compared to the original. Halo 2 had online multiplayer on consoles and dual-wielding for certain weapons. Super Mario World has a number of world maps that connect each level, unlike the original trilogy that just had numbered levels. There are some games though, that seem to take away from what was there before. Bioshock 3 for example only lets you carry 2 weapons at a time and gives you an overshield like it wanted to be Halo. Unlike Bioshock 3 though, there are games with less that are actually good though!
(There are modern RPGs that aren't as RPG as this RPG)
Grand Theft Auto: San Andreas is essentially a role playing game. You play as Carl Johnson and throughout the course of the game you watch as CJ goes from a street thug and grow into a high-profile crime lord. Between missions, you have a lot of freedom when it comes to CJ’s activities and depending on what you do CJ will change. If you go biking, CJ’s stamina is strengthened. If you lift weights, CJ gains muscle mass and punches harder. If you overeat at one of the several different fast food chains, CJ gets fat and loses the ability to sprint effectively. The more you use specific weapons, the more skilled CJ gets with them: he reloads faster, he aims more effectively, etc. The more you drive, the more you boat, the more you fly, everything you do with CJ makes a skill bar tick up and there are noticeable differences between an experienced and an inexperienced CJ. A CJ who has picked up a pistol for the first time can shoot out a tire after aiming for a moment, whereas a fully trained Akimbo-CJ can pop multiple tires and hit the gas-tank of a car in about the same span of time, in theory. When it comes to straight-up plot progression though, any CJ can theoretically make it from the beginning of the story to the end.
Grand Theft Auto IV was the first Grand Theft Auto to launch on 7th generation of game consoles; the Xbox 360 and Playstation 3 respectively. The graphical difference between GTAIV and GTAIII is remarkable; the new game featured a lighting engine and enough onboard memory to make buildings, vehicles, character models, and set dressing (like bottles, street-debris, furniture, store fronts, etc) look fairly realistic, especially for the time. Liberty City has never looked this real, the vehicles handle wildly differently, and the overall plot is a grounded tale of revenge and redemption. Compared to Grand Theft Auto: San Andreas though, there isn’t as much as there used to be.
(Cousin! Let's reconsider revenge and play darts instead!)
In Grand Theft Auto IV you play as Niko Bellic who can eat 50 hot dogs in a row without changing his body mass at all. Niko Bellic cannot ride a bike, he can’t customize cars, he can’t work out or wake up out-of-shape one day. There are roughly 17 different weapons Niko can use, whereas CJ had access to roughly 34. San Andreas has 6 diners, 3 fast food places, and a handful of restaurants, each with variable menus. Grand Theft Auto IV’s Liberty City features a diner, hot dog stands, vending machines, and Cluckin’ Bell, each without a menu. Then there’s the size difference between Liberty City and San Andreas. The area of the map in San Andreas is 12.7 square miles and features several different biomes including a desert, a Las Vegas analog, a Las Angeles analog, and a San Francisco analog, complete with Pacific ocean.
I couldn’t find a map of Liberty City in square mileage, but it isn’t as diverse and seems to excel in verticality rather than spread. Liberty City has analogs of Brookland, Manhattan, Queens, The Bronx, and bits of New Jersey, along with the Atlantic Ocean. There are highways in Liberty City, but driving in San Andreas has so much more variance in comparison. There are small desert towns, valleys and canyons to drive through, densely packed cities with their own aesthetic, but in Grand Theft Auto IV it’s all city all the time. It isn’t like there’s a lack of nuance; there are richer parts of Liberty city, there are dirtier, run down parts of the city, there’s an industrial district, but it’s still more city than not.
Ultimately I don’t think Grand Theft Auto IV isn’t a lesser experience compared to San Andreas, even if the older game has more features than the newer one. The physics engine in GTAIV allowed for animations and interactions that weren’t possible in those previous games. The intimacy of the narrative was also refreshing compared to San Andreas which felt overwhelmingly wide. The point of Grand Theft Auto IV wasn’t Niko Bellic changing his body while operating a chop shop and buying up all of the properties in New York, it was a story of finding the people who sold him out and taking bloody revenge.