One thing I dislike in game play - especially in GURPS, with its one-second time scale - is post-odd calculation take backs.
Player: "I shoot that orc."
GM: "Okay, roll for it."
Player: "Let's see, shooting between my two buddies and past that other orc, 8 yards, uh . . . I have a 7 to hit. Nevermind, I'll shoot this other guy."
In some ways, doing this is fair. You check the swing, or hold the shot when you realize it's bad. Generally, if you balk to an aim-like or wait-like action (Aim, its melee equivalent Evaluate, or Wait) it feels okay and realistic.
When it gets changed to something else, or only after a long calculation, it feels very gamey. "Nevermind, instead of attacking I'll Move." So you decide to attack, change your mind, and then move as fast as the guy who knew he'd move?
It feels very gamey - sure, you can say "My character never weighed all these options, I did as a player, and then he reacted with his usual preternatural panther-like grace and speed!" I accept that. But it doesn't feel that way, and we all know you decided against it after finding out your actual odds of hitting (or after the guy next to you says "No, don't do it, I'll do this other thing so you should do something else.") It feels like what it is - you're making decisions based on in-game odds of success after you calculate them, and taking a lot of time to do it. And it avoids the very real issue of people balking or backing off a decision after making it, or taking some extra time for it (which is something Doug Cole talks about).
Plus it's one of the mortal sins of my games - wasting time. Saying "I shoot the orc" and then quickly calculating your hit odds and rolling takes a lot less time than doing the same, not rolling, and then doing something else. It's breaking up the flow of the game. It makes each turn take longer, which means longer fights, less stuff done, and more waiting by other players. You make us take time to figure out rolls that never get rolled. Please, no, just take the risk.
Generally here is how I run it:
- decide on your action.
- say you'll do it or not.
- figure out the roll you need.
No calculate-then-change your mind. You decided, now we're just finding out if it worked, not if it's worth trying.
Now, there is a clever player dodge - quietly figure out the odds between turns, while you wait for someone else to go, and decide if you'll do it or not. Okay, you're being pro-active and not wasting time. I'm totally fine with that. Why? Because of the "not wasting time" part. You're putting work in ahead of time to save time on your turn. That is good and courteous play.
But what if you want to allow checking, balking, or changing your mind? After all, a warrior might realize he made a bad decision and then not go through with it. Plenty of time you start to make a move and then realize it's a bad idea and try to stop it. Baseball has a whole set of rules for that, and fighters will debate whether it's better to follow through on the wrong move forcefully or suffer the consequences of a halted movement.
In the post I linked above, Doug proposed a roll-based solution. Here is my own twist:
The Roll-Heavy Solution: Force an IQ-based skill roll (to realize it's a bad idea) or a DX-based skill roll (to check your attempt without putting yourself in a bad spot. On a success, you check your action, and your turn ends - treat it as "Do Nothing" for all purposes. On a critical success, you can choose another action without any penalty. On a failure, you go through with the action. On a critical failure, you suffer some kind of mishap - a roll on the Critical Miss table, or you pay for the spell but don't cast it, etc.
Optional: Halting and changing your action to Aim, Concentrate (to keep a spell up, not to cast a new one), Evaluate, or Wait (with a trigger aimed at your current target) - against the same target - does not require a roll.
Notes: You can change the roll to Tactics, best melee weapon skill or best ranged weapon skill (depending on the type of attack), spell skill roll, Thaumatology, or other skill. You can make it Per-based if you think it's a question of seeing the problem instead of understanding (IQ) or reacting to it (DX).
The No-Roll Solution: You can change your mind later, but you can only change your action to Aim, Concentrate (to keep a spell up, not cast a different one), Evaluate, Do Nothing, or Wait (with a trigger aimed at your current target). No roll is necessary; just announce your replacement action and execute it.
Neither of these has been play-tested. On paper, they sound okay. Personally I just do the "Do or don't do" binary decision, and figure once you start calculating your chance to hit you've committed to the action and the roll. But one of those approaches might work for changing your mind in combat.
Thanks to Doug for sparking this idea.
Note: I'm not talking post-roll or post-consequence take-backs. "I drop the grenade and read my pistol!" "Oops, you armed the grenade, remember? It explodes at your feet." "Oh, wait, no I don't drop it." Yes, yes you did. I don't allow those kind of take-backs. It's the "I cast this spell, oh wait, 7 is too low, I do something else" bit I don't like.
[Editing Later: Check the comment by gnomaszgames below. It has a great suggestion - use the Opportunity Fire/Target Discrimination rules (p. B390) for the mechanics of changing your mind mid-move. I like it!]