The game itself is simple, yet surprisingly complex. The game utilizes the SPECIAL system, which provides amazing versatility in character creation and execution. Skill tests are made using a combination of environmental factors, skill level and stat modifiers. Your character has a certain amount of space for equipment, armor and weapons.
For its time, the world of Fallout 2 was huge. There are easily 60+ hours worth of content in the game. The other trick of the game is that it can be amazingly short as well. There are certain loopholes which can be exploited to finish the game in under 30 minutes. Part of the sandbox style of play is that after the intro area, the game is completely non-linear. You can travel to any location you wish and play the game in any order you wish. It may not always be the smartest idea to go to certain places right off the bat, but you can!
Along with witty dialog and an epic storyline, Fallout 2 is packed with pop culture and obscura references. For instance: one random encounter has you running across a crashed USS Enterprise Shuttle from the original Star Trek. The deceased crew scattered around the shuttle are all wearing red uniforms.