"evolution of games" on the PC?
198X-1993 = ports from other systems and making the games worse, with the occasional pc only gem (wolfenstein for example)
1993-1996 = doom clones, C&C clones
1996-now = quake/half life clones, splinter cell clones, C&C clones
1999-now = MMORPG clone after clone
The pc was never an original platform for games IMHO.