There's a common misconception that Riddleof Steel is a combat dominated game, after all it's what we all talk about. However there are actually @65 skills available to a character. Each is rated as a task number, roll a relevant attribute dice pool and each dice getting that number is a success. The more, the better the success level. The thing is, that's it. If we don't talk about it more, it's because it's fairly straightforward.
We harp on about combat because that's where TRoS differs from many other games. Others here have described the mechanics. I just want to add a note about the consequences for playing. For me it's all about making decisions.
Most games (from D&D to Earthdawn, Runequest to Harnmaster) promote player decision-making right up to the point of contact. Then suddenly we are on auto-pilot.
Roll (or check for pre-determined) initiative.
Say who the character will hit.
Roll to hit.
Roll damage (in some cases, roll for hit location).
Roll to parry (or await the effectiveness of your armour class).
Most games now offer a few combat option but these are usually tinkering around the edges, a bonus here in exchange for a minus there. Apart from saying who we will hit, the GM could do all this on computer and phone us later with the outcome (I've heard of one or two GMs that do!) I know I'm talking exteme cases but it's perfectly feasible.
If TRoS is different, it's because it forces the players to make choices at every stage, exactly as they would have to do in a real fight.
Normally one person hits each exchange. The declaration is simultaneous. Do you attempt to get in first and contest the initiative? If your opponent defends, you can try and hit. If they also try to hit, the fastest will go first (against an opponent who's trying to attack, and is not defending at all). If the person attacked first is still standing, they can hit back at the non-defending opponent. A risky choice. You can always opt to defend at first and try to wrest the initiative from your opponent.
If you're hitting, you decide where (hint, go for the weak armour points), whether with point, edge, or blunt, and most importantly how much of your effort are you going to put into the attack and how much are you going to hold back in case your opponent defends successfully and attacks back. This is where you split the dice pool; don't be fooled into thinking it's a guessing game, it's a deadly calculation of how much you are willing to risk to take down your opponent. You know how many dice you have available and can see how well armoured your opponent is, and will quickly learn how roughly how good they are (as you see how many dice they are committing to the fight). You have to choose.
Additionally while you have a set dice pool for longsword, for example, when fighting, you select one of a number of moves linked to that weapon (cuts, parries, counters, beats, etc.) which also have an influence on the outcome of each exchange.
Damage in the end comes from your attributes and the weapon used along with how well you succeeded in the attack and is rated by the number of dice lost from the pools for shock, pain and blood loss. It can be minor or catastrophic, but there aren't many games in which it's a valid tactic to hit your opponent for a moderate wound and then defend while they struggle and eventually collapse before you from blood loss. OK, I know that's not heroic but it's feasible.
The mad thing is that because the system all runs on the dice pools available and the dice added or subtracted to the pool according to the situation, the turnaround for each exchange is very quick. TRoS runs as quickly as D&D3E or Runequest and quicker than Earthdawn or Harnmaster.
The trick in TRoS is not to get onto a fight unless you are prepared to risk death. Spiritual attributes where appropriate add dice directly to the dice pool so a moderately good or injured character can turn into a fearsome warrior ("my name is Inigo Montoya, you killed my father, prepare to die!") The system is dangerous but it is survivable with thought and daring; and it is heroic in the real sense - you may be scared (of losing the character) but if something has to be done...
Anyway, that's my "note" on the difference that the choices in TRoS make to my gaming. YMMV as ever.
Dave