I know it gets a bad rap for the complexities, but most of those are only in character creation/leveling, and in enhanced options for 'realism'. Once you get rolling, and have computed your offensive bonus/defensive bonus, it's very fast moving- very few modifiers are required, and only one roll per attack (or two rolls if you get a critical).
And the criticals are very deadly (and amusing), and the trauma delivered can cause trauma to the players (just kidding, but seeing your character go through that type of experience can be traumatizing).
The other thing that I really like that helps to mitigate the deadliness is the ability to defend. You get a basic defensive and offensive bonus from your weapon skills and shield and agility (there are some classes that get another bonus to represent unarmored quickness, but those are rare). You can trade your offensive bonus for a chance to defend against the incoming attacks.
The system is open ended d100 based (roll a d100- if you get less than 5 or greater than 95, roll again and subtract/add), and use charts based on the weapon type. The criticals are similarly d100 based, but not open ended, with a separate critical chart per damage type (slash, crush, pierce, burn, etc).
An example of combat: Jakin - 1st level rogue was hired to break into
the room of Kallem, a 1st level warrior, and steal back the money the
mercenary had just been paid. Kallem came back to his room early, and
caught Jakin in the act, and has no plans to call the guard in to kill
Jakin charges Kallem with his shortsword, figuring that a good offense
is the only thing that's going to keep him alive, as Kallem pulls his
long fighting knife.
Framing the combat, the GM pulls out the Dagger attack table and the
Short Sword attack table, and notes that the dagger does Slash,
Puncture, or Crushing criticals, and the short sword does Slash,
Puncture, or Crushing criticals, so pulls out those three tables also.
Jakin has an OB with the shortsword of 62, and a natural DB from his
agility of +10. He's wearing leather. Kallem has an OB with the
dagger of 81, and a natural DB from his agility of +5, and is
unfortunately not wearing his armor.
They roll initiative on D100 + their quickness modifiers... Jakin gets
a 78, and Kallem a 52, so Jakin goes first.
Figuring to end this quickly, he goes almost full out with his weapon,
using 50 OB, and parrying with 12 for DB, bringing his defensive bonus
up to 22. Kallem defends 30 of his offensive bonus, bringing his DB
up to 35, and saving 51 OB for his return attack.
Rolling D100 for 46, Jakin adds 50 to the roll getting 96. Consulting
the short sword chart for Kallem's armour type (1 for clothing), he
gets 14CP. This means that Kallem takes 14HP, and the roll is D100 on
the C column of the Puncture critical table. He rolls an 81 - Strike
bites into foe's ribs. The impact sounds truly terrible. +6H,
stunned, no parry for 3 rounds, -25 to all actions while stunned,
Kallem's in a bad place, and takes his stun this round instead of a
return attack. New round, and Jakin goes full out trying to finish
Kallem. The warrior, now regretting his bravado, is going to make a
will roll to overcome the pain and scream out for help. But Jakin has
the initiative, and rolls 52 + 62 - 5 for Kallem's agility bonus (no
parry) = 109. Again consulting the Short Sword table, that is 17HP,
and a D on the Slash table. He rolls a 92 - Sever foe's weapon arm
and bury your blade into foe's side - Foe falls prone, and is in shock
for 12 rounds, then dies. +15HP, stunned with no parry for 9 rounds.
Rolemaster has a lot of options, and even at it's easiest does have a bit of an overhead (the character creation especially, and in combat, the charts). Add in modifiers for different things such as stance, weapon speed, etc- and it gets pretty ridiculous. But at it's basic, it's not too much to handle and goes very quickly, and is very deadly. I've had characters that I've invested a lot of time in (and not just character creation, but playtime) get killed suddenly because I wasn't on my game, or wasn't paying attention- or just bad luck. But that makes the ones that are successful that much more rewarding.