That's more or less up to you as the GM. Risus "combat" isn't always about fighting and at the same time, fighting isn't always "combat." “Combat”
depends on multi-round jockeying and wearing each other down … but
many conflicts are too sudden
to be played that way (two characters grabbing for the same gun, for
example). Such “Single-Action Conflicts” (SACs) are settled with
a single roll against appropriate Clichés (or inappropriate Clichés,
with good roleplaying). High roll wins. Note that, in nearly any
case, the Game Master may jump between the three resolution methods
(Target Number, Combat, Single-Action Conflict) to suit the pacing
and mood. Sometimes, an arm-wrestling match works best as a combat …
sometimes it works best as a Single-Action Conflict, and sometimes
(preferably if it’s against some kind of coin-operated
arm-wrestling machine) even as a simple Target Number. -Risus v2.01 p.3 In your example where a dude is armed with a .357 magnum taking aim at a boxer, I might not call it a combat. I'd probably just have the PC roll against a target number. "Okay, roll on your Mall Ninja cliche. 5 or better you wound him, 10 or better he's toast, 20 or better and you splatter your choice of internal organs all over the wallpaper. It's gonna be a pain to clean later, fair warning." If someone didn't have a directly applicable cliche, the target number would be revised higher: Guy Who Claims To Be A Navy Seal But Wasn't (4) might need to roll 25 or better to hit and so on. If you as the GM think that a straight challenge isn't fair or fun , then you can opt for a contested roll. So, your Mall Ninja (4) rolls against the "Float Like A Butterfly, Sting Like A Bee" (2). Winner gets to decide what happens to the loser as usual. You could always give a bonus die or two to the Mall Ninja given he has a more effective tool. If you want Risus combat, you might need to adjust the time scales to get something that works best with the system. And this is where the magic kinda happens with Risus. The combat doesn't necessarily begin when the gun is drawn. It might begin in the set up, "You see the boxer start to approach you. He's looking pretty intimidating and opens the combat with his Leg Breaker For the Mob (3) cliche." Win that first round and the boxer is less effective when the shooting actually starts...lose and now your aim is unsteady. There's no wrong way to play with Risus so use what works at that specific instance. You can always just say yes and move on. "Great, you shot him. There's a big mess on the floor and he's making gurgling noises. What next? Is that sirens you hear in the distance?"