Top 5 most influential games of all time:
1. Pong: Well, this one is kind of a "Gimme" as it's the grand daddy of them all. Every game that followed was based on the idea that you could play a game on your television. Thankfully, the graphics improved over time. ;)
2. Tetris: For a long time, Gaming was the convention of nerds and shut ins. Tetris finally made video games an "acceptable" way to pass time. Now, your girlfriend could play with you. Heck, my MOM plays Tetris.
3. Wolfenstein 3D: Originally a shareware game, this free ware broke conventions and introduced the concept of a "First person shooter" or FPS. Now, you can SEE what your character is seeing! a tad antiquated by todays standards, but mind boggling back in the day.
4. Metal Gear Solid: COMPLETELY reinvented the warfare/combat spectrum of gaming by introducing one key concept: Tactical espionage. Thousands of teenage boys scratched their heads in unison and said "you mean, I don't have to just kill everybody I see? That it's actually SMARTER to just sneak around?"
5. Halo: Oh, how far we've come since those halcyon days of Wolfenstein 3d! The release of this game, and subsequent sequels have set the benchmark for sales around the world. Thousands (if not millions) of players worldwide, an upcoming anime, and it's own toy line, there's certainly no denying that the HALO brand has had quite the impact on how we view video games as a viable market commodity, seeing as how it's made more money than many hollywood blockbusters.