Saeviomagy said:So what is it? Just more deadly combat bolted onto D&D?
Nope, it's a separate game. The basic mechanic is dice pools - you roll a bunch of dice, and every one that's over a given target number gives you a success. The number of successes you get determines whether you succeed or fail, and by what margin.
TROS' combat system is really interesting in two respects; the first is that it's very deadly, and appears to be pretty realistic without being hugely complicated. The second is that skill at using the combat rules is actually a fairly major factor in determining who wins. Out-thinking your opponent is a critical part of surviving fights, which is pretty neat IMHO.
The magic system isn't mechanically complicated, but it is very freeform and spellcasters can be very powerful. There isn't really any pretense of balance - a spellcaster who's willing to pay the price can accomplish some pretty fantastic effects, the only balance to his power is whether it's worthwhile shortening his lifespan to do so. That's the price of magic, it ages you prematurely; the tradeoff wouldn't make much sense in a standard D&D setting, but it works well in TROS because character goals and motivations are an intrinsic part of the advancement mechanics.
Others have covered those advancement mechanics pretty well.
The final really interesting thing about TROS, IMHO, is the campaign world. It's one of the better Earth-inspired settings, and I really wish they'd published it in a full book of its own. Particularly good, IMHO, are the various religions, which are close enough to real world religions to be recognizable but sufficiently different that players can separate their own beliefs from their characters'.
It's not a good game for a kills-things-and-take-their-stuff playstyle. But in its niche - character-driven crossed with grim-n-gritty buttkicking - it's a darn good game, IMHO. Lots of good stuff at the website, too:
http://www.theriddleofsteel.net/