I bit. Let's take a look at what I just bought:
Call of Cthulhu: Dark Corners of the Earth: Never played it.
Commander Keen: Only played the shareware version.
DOOM 3: Only played the demo.
DOOM 3 Resurrection of Evil: Only played the demo of the game it's an expansion of.
DOOM II: Only played bits and pieces of it.
Fallout 3: Pirated and beaten, but not with any DLC.
Final DOOM: Only played the shareware version, later pirated for the multiplayer but only played a bit of Episode 2.
Heretic: Shadow of the Serpent Riders: Only played the shareware version.
HeXen II: Only played the shareware version.
HeXen: Beyond Heretic: Only played the shareware version.
HeXen: Deathkings of Dark Citadel: This game sounds like bullshit.
Master Levels for Doom II: Never played it.
QUAKE: Only squinted my way the shareware version.
QUAKE II: Only played the demo, later pirated for multiplayer.
QUAKE II Mission Pack: Ground Zero: Never played it.
QUAKE II Mission Pack: The Reckoning: Never played it.
Quake (not QUAKE) III Arena: Pirated for multiplayer, which is the only thing you can pirate it for anyway.
QUAKE (not Quake) III Team Arena: Never played it.
QUAKE Mission Pack 1: Scourge of Armagon: Never squinted my way through it.
QUAKE Mission Pack 2: Dissolution of Eternity: Never squinted my way through it.
Return to Castle Wolfenstein: Only played the demo.
Rogue Warrior: Never played it.
Spear of Destiny: Never played it.
The Elder Scrolls III: Morrowind: Pirated but only got as far as dicking around some dwarf ruins.
The Elder Scrolls IV: Oblivion: Holy shit I bought this game! But not the DLC.
The Ultimate Doom: Oh wait this is DOOM 1, not Final DOOM. Well excu-use me.
Wolfenstein 3D: Say it with me: Only Played the Shareware Version.
I think I just paid $70 to erase a history of cheapskate laziness rather than serial larceny, but whatever. I now have enough new games that if I quit my job and did nothing but play them all day I'd probably not be done until next year. If I had the time for it I'd do something ridiculous like Let's Play Every id Game Ever Except Those Two Quake Games, but I don't, so leave me alone.
I do plan to play them in chronological order starting from Commander Keen all the way up to You Don't Die in the Ending Now, but God knows when. I think I might just do the entire backlog like that.