Video games are inherently limited by two things: Their implimentation and their content. Implimentation is a simple thing to fix: re-release an improved version of the game on a newer, faster, or better console/operating system and rework the mechanics of it. The base game doesn't change much, just the means of playing it.
Content, on the other hand, is not as readily fixable. At shipping, each game has a finite amount of content. Even games like Neverwinter Nights and the Elder Scrolls series have limited content, even if they have huge worlds. There's only so much that can exist in these game discs, and only so much that random creature generators can do for these games.
There are two solutions to this problem. The first is randomness. There's an ASCII graphic game called Dwarf Fortress that can generate from scratch it's own random game world with random towns, people, and places. Now, this does allow the player, if they tire of a world, to create an entirely new world, but at the moment, the world has very little impact on the actual game. There's an adventure mode where you can wander around and interact with the world, but it really doesn't matter that much.
The concept of a random world/plot is a dangerous one to rely on as well. Random generators are flawed because they are random. Yes, you cannot tell where it is going, and you will be surprised, but more often than not, the random generator creates something that defies logic and doesn't work well for a game basis. A randomly generated game is very rarely balanced, and a lot of work has to go into it to make it work.
The other option is to use player generated content, a la Spore and most MMORPGs. The idea is that other players will create content and fun for players that is beyond the standard gameplay. For MMORPGs, this is anything social and interactive, whether it's raids, guilds, contests, or just the experience of seeing a hundred adventurers standing around in their various gear, and seeing the potential of the game.
For a game like Spore, the content is directly created by other players based on the same rules you are playing with. Spore creates predator and prey creatures around your creature based on profiles pulled from their web server. These profiles were creatures generated by other players, using the rules that you are bound by. This creates unique, but relatively balanced ecosystems. The problem will arise when someone finally breaks the mechanics of the game and generates a super-predator or unkillable/uncatchable prey. There will be problems with this system, and it will need to be monitored carefully.
Content is a serious issue with video games, as if a game runs out of content, the player will not keep playing it. Along this same token, next time I will look at the viability of expansion packs to solve this problem.