I'm clocking in at 20.

In the last two years I have played:

D&D 4th Ed (two separate campaigns)
Call of Cthulhu
Dragon Age (one shot)

Planning on starting a D&D 5th Ed game next month.


-TGA

According to my logs, since 8/1/2012 I've played:

D&D 3.5
Star Wars D20
Eclipse Phase
Slingtown (homebrew)
Alternity
OD&D
Godlike
The Last City (homebrew)
Call of Cthulhu
Lady Blackbird
Shab-al-Hiri Roach
Numenera
World of Darkness: Innocents
Technoir
Murderous Ghosts
Better Angels
Trail of Cthulhu

So, 17 games total. 15 if we don't count unique homebrews.

• 0D&D
• B/X D&D
• AD&D 1e
• D&D 5e
• Blood and Treasure
• Microlite
• Star Wars the Edge of the Empire
• GURPS Transhuman space
• Gamma World 2e
• Hollow Earth Expedition
• Night's Black Agents
• Trail of Cthulhu
• Shadowrun
• Fate of the Norns
• Hero Kids
• EABA
• Traveller
• RuneQuest
• Dungeon Crawl Classics
• Pathfinder
• FATE Kerberos Club

I think that's it

In no particular order
I Played

• Shadowrun 2/3
• Aces & Eights
• AD&D 1/2
• MechWarrior RPG
• 3 Different Homebrews
• Hackmaster Basic
• Call of Cthulhu
• 5e
• Classic Traveller
• Champions/Fuzion

I Ran

• Dragon Age
• Song of Ice and Fire Roleplaying
• Conan D20
• Shadowrun 2/3
• Cyberpunk 2013/2020
• The One Ring
• Yggdrasil
• WFRP1
• MRQII/Legend
• Runequest 6
• Dark Heresy/Rogue Trader/Deathwatch/Only War
• Hackmaster Basic
• Aces & Eights
• DCC

In rough order of in-game time spent the past two-ish years:

DDN playtest
Star Wars Saga
Savage Worlds
AD&D 1e
Deadlands classic
D&D 3.5

Hmmm....counted wrong on my vote.

Oh, I forgot that I tried and failed to run Cortex Plus. Three or four sessions, and it wasn't the system that collapsed-- though it has the same problem as Fate, in that there's not enough advancement.

Spelljammer - long running campaign
Star Frontiers
Gamma World 2nd
Gamma World 4e D&D - very briefly
AD&D - ongoing campaign
BX D&D
RuinsWorld (kinda counts)
Mythic - briefly
Call of Cthulhu - End Time (Was also one of the playtesters wayyyyyyy back)
After the Bomb - briefly
Emergent - early playtest
Tunnels & Trolls
Legends of - The Time & Space version and looking to try the Untamed West version later.

AD&D 1E as DM & Player
Other Dust (GM)
Mutant Future (GM)
DCC (Player)
Rifts (Player)
Currently playtesting a homebrew called "The Lost Star" which is d12 and skill buy based. Really light with a strong sword and planet vibe. Kind of feels like a mix of Barsoom and Fantastic Planet.

Fate Core*
D&D 4e
Pathfinder
Legend of the Five Rings 4e
Marvel Heroic Roleplaying*
Edge of the Empire
Savage Worlds*
Numenera*

EDIT: Somehow forgot my Numenera Campaign, it didn't last long because one of the players had to move for work and another had a radical schedule change in his job.

The ones that are starred are the ones I ran, the others are ones I played in.

Quote from: FaerieGodfather;775075Oh, I forgot that I tried and failed to run Cortex Plus. Three or four sessions, and it wasn't the system that collapsed-- though it has the same problem as Fate, in that there's not enough advancement.

Why would you be expecting advancement after so few sessions?

Not nearly enough:

DCC
Savage Worlds
D&D B/X
Hillfolk
Night's Black Agents

In order of first game, over the past two years:

GURPS 4E (20 sessions GM, 2 player)
Fate Core (4 sessions GM)
Savage Worlds (6 sessions GM)
Swords and Wizardry Complete (54 sessions GM)
Call of Cthulhu (4 sessions player)
Risus (2 sessions GM)
Covert Ops / Delta Green (2 sessions GM)
Dungeon Crawl Classics (2 sessions player)
The Price of Freedom (1 session GM)

GURPS all but exclusively; Savage Worlds as a one-shot.

Five. GURPS, AD&D, Pathfinder, Call of Cthulhu, and Rogue Trader.