There are several aspects I believe to be critical for the development and deployment of a successful video game. The first being the ability to learn and grow while playing the video game including but not limited to; leveling up, health advancement, weapons / spell upgrades and just all around different ways to defeat your enemy in general.
When I play a game that does a good job in submersing me in my surroundings, making me feel more in touch with the game and the other aspects within the game, this increases my wanting to succeed. I also feel that a good tutorial / training level is important to the success of a game, if the player has no idea how to do something it is going to make it hard to keep their interest in the game longer, decreasing the re-playability value.
Some of the other aspects of game development that are critical: high quality graphics, large levels that are free roaming, ability to differentiate between other games, online and multi-player playability. Storyline and character development are also important. This can help to maintain a strong fan base.