Wading through a single elimination bracket for every genre would take a very long time, so I would use a two-stage process (nomination and voting) instead. In the nomination round, you submit your picks (say 5 to 10) in each genre. The top 8-or-so nominees in each genre face off in the voting round, in which you list your first, second, and third favorites in each category. I would then tally the votes and announce the first, second and third-place winners in each genre.
The challenge here is defining the categories. I think genres merely labeled "Action," "Strategy," etc., would be too broad and not very interesting. So, after much thought, I've defined no fewer than 16 genres! (I actually came up with more, but decided that I had to minimize and 16 is the lowest I can go.) Now before you call me the Crazy Guy, I propose breaking the 16 genres into two competitions of 8 "events" each. We'd do 8 events now and the other 8 later in the year. Behold the Octopus Overlords Olympics:
Summer Olympics (the more action-packed games)
- Action Singleplayer (e.g., most FPS including the stealthy ones, the Crusader games, Deus Ex)
- Action Multiplayer (e.g., Counterstrike, Planetside, the Battlefield games)
- Action-Adventure (e.g., Tomb Raider, Beyond Good & Evil)
- Action-RPG (e.g., Diablo, trader games like Pirates and Star Control II)
- RTS
- Realistic Sim (realistically modeled flight, military and driving sims)
- Whimsical Sim (space sims, the Mechwarrior games, the more arcadey racers, etc.)
- Sports (both action-oriented and spreadsheet)
- Puzzle & Arcade (e.g., Popcap's games, scrolling shooters)
- Adventure (both graphic and text)
- RPG
- MMORPG
- Building Sim (e.g., the SimCity and Sims games, "Tycoon" games, many of Bullfrog's games)
- Grand Strategy (e.g., 4X games, the Total War games)
- Turn-Based Tactics (e.g. HOMM games, squad tactics games like X-COM)
- Wargame (e.g., the 5-Star General games, Combat Mission games, Close Combat games)