I don't call 'em clones because they're not. They can't be, for legal reasons.
I also take issue with 'retro' since it's so subjective and often partial... game x is part retro part new.
C&C is the best example there, using an ascending AC system (ala D&D3, 3.5, 4).
Hack is 1e-odd, a parody that became a realgame. Hard to categorize, one-of-a-kind.
My view of RPSims (those that rewrite but reproduce
OOP FRP game systems) is:
2006 BFRPG (Gonnerman) and
OSRIC (Finch, Marshall)
2007 Labyrinth Lord (Proctor)
2008 Swords & Wizardry (Finch)
2009 MicroLite (Drebitko) and Spellcraft & Swordplay (Vey)
2010 Dark Dungeons ("Blacky")
("Blacky the Blackball" seems paranoid about the legal stuff; I have a real firstname but no last name.)
There are various non-fantasy as well, notably by Proctor.
Any corrections? Any additions?