5. Doom (1993)
Doom appeared seemingly out of nowhere as the spiritual successor to id Software's Wolfenstein 3D title a year earlier. Instead of going around killing Nazis, however, you were a space marine looking to save your cadets from a mysterious alien uprising...from hell. Yes: Hell. And sure, Dead Space may have cribbed some of its plot from this classic, but imitation is the most sincere form of flattery, especially in video games, where the technology grows, but the fundamentals stay the same. Of course, it's a case of suffering from success: Doom's effect on the industry was wide-reaching, goading a whole new subculture within the industry to begin churning out similar games cut from the same cloth. The series has fallen on rocky times in recent history, and hopefully, they can find a way to reclaim their former glory in the near future (lest the next generation of gamers need to ask you what 'BFG' stands for).