So, as I posited in previous posts, there are several "levels" of play that you might wish to run using the Delraith setting. Some of these might need their own system, somewhere down the line, but for now, I'll suggest what I would run them with.
First is the one it was designed for - the Kobold Ascension Campaign. Starting as the lowest of the low, level 1 Kobolds, and sneaking and cheating your way to Godhood while avoiding the attention of the other Dragons. Runs sorta like D&D meets Paranoia. I would suggest Old D&D or GURPS, if you want to run it as a serious, deadly game - or Risus, if you'd rather it be about PvP banter and situational comedy. I see both as equally valid ways to play this one out (and I'd personally lean towards Risus).
Second would be your Standard Fantasy Adventure - there are old civilisations, ancient ruins of bygone eras, terrible Powers and Dark Secrets to be unveiled by those brave enough to look. Runs quite well as your usual D&D-esque Adventure Time, with plenty of stuff to find and things to kill. I'd use something like "new" D&D, Microlite20, maybe Savage Worlds, to maintain a feel of "high adventure". FATE could also be a good suggestion, for less combat-oriented games.
Third, a "middle ground" where the players control powerful Nobles of one of the more auspacious Houses of Valerian's Reach - their hand can be seen across the continent. Runs like a smaller-scale Rogue Trader, and hell, you might be able to alter the system enough to use a lot of it as-is. I'd use FATE, and maybe port over some of the Rogue Trader mechanics, where I could (like Profit Factor - much better than counting every gold piece...). Or Birthright/AD&D, but the system wasn't a good fit (though some of the large-scale rules could be useful). The outlier is REIGN, by Greg Stolze - a lot of people rave about it, but I've never tried it. It's got Company Rules that could be pretty useful...
For a more high-powered game, there are the Dwarven Reclamators - squads of Dwarves, clad in the finest armour, weilding terrifying weapons, on a mission from God Himself to reclaim the ancient relics of their kind, to remove threats to their fortress homes, and to generally be fucking terrifying. Plays out much like a fantasy counterpart to Deathwatch. And, indeed, you could try and hack the DW system to fit, but I'd use something like high-level (and equipment) D&D, or maybe Mutants and Masterminds, to represent the weird technology the Dwarves are using, and to allow a lot of variance in the characters despite a common race.
Finally, Dragons. Any of the Serious Risus hacks would be perfect to represent the god-like power level without ridiculous stat inflation, as would FATE. However, check out the old Council of Wyrms campaign setting for D&D - lots of useful goodies to be nabbed from there (even if you'd be playing high-level dragons...)
I'll post up more about each level as it comes to me.