31.
I started off on Fighting Fantasy gamebooks, then Grailquest and Lone Wolf.
My first real RPG was Tunnels and Trolls, moving swiftly to collecting all the TSR D&D boxed sets, TSR's old Marvel Super Heroes game, FASA's Star Trek, Mayfair's DC Heroes, GW's Judge Dredd and Warhammer Fantasy Roleplay, then onto AD&D 2nd Edition, Traveller: The New Era, and finally Advanced Heroquest (although I later managed to grab enough pieces from eBay to put together a Warhammer Quest set)
Then there was a bit of a pause in RPG activity when I moved into Wargaming with GW's Warhammer, Warhammer 40K, Blood Bowl (which doesn't really fit any category nicely) and Space Marine (the old Epic system), moving onto Titan Legions and Epic 40K.
Around this time I set up my side business in RPG retail for some local clubs, and grabbed Call of Cthulhu, White Wolf's Vampire, Werewolf and Mage, then LUG's Star Trek, D&D 3E, back to Wargaming with Epic Armageddon, and back to RPGs with Mongoose's Judge Dredd, Decipher's LotR and Star Trek.
Finally (and most recently) Mongoose's Babylon 5, Conan, Armageddon: and Lone Wolf games, and launched the online side of the business.
I haven't included the games I bought purely as a collector, and I'm sure I've forgotten some others...