Just got the game. I'm wondering about tinkering. I'm assuming that this card when played substitutes its subroutines for those on an ICE card, that is, it forces the ICE, rezzed or unrezzed, to take on the subroutines shown on the Tinkering card rather than on the ICE card?

Your terminology is a little off, and that might be what's leading you astray.

Subroutines are the things that the ice does - they always have a little arrow symbol in front of them, like "-> End the run." or "-> The Runner loses [Click], if able."

Tinkering doesn't change the subroutines on an ice at all.

Traits are the words on the side of an ice (and in the middle of all other cards), like barrier, sentry, AP, trap, code gate, transaction, region, etc. These have no affect on the game inherently, but may be referred to by other cards. (Most icebreakers refer to either the barrier, sentry, or code gate traits.)

What Tinkering does is it looks at the list of traits that an installed piece of ice has, and adds to that list the barrier, sentry, and code gate traits, thus increasing the number of cards that can successfully refer to it.

I hope this helps.

Ah, now I understand. This is very helpful, thank you, and is exactly what I needed to know. You're right, the way I was reading and thinking about this card, I was thinking Tinkering changed the subroutines themselves, which wasn't making sense as it seemed to make the ICE more powerful. I wasn't thinking about the traits. So if an icebreaker doesn't have a trait that matches the trait on the ICE, it can't affect the subroutines on that ICE at all. Got it!

Thanks again!

Adding to this; my opponent played tinkering on a piece of ice before I even rezzed it, he was rather determined to get through. Now, while I have no problem letting him waste a card like tinkering on a piece of ice he already has an icebreaker for, I would like to know if you're even allowed to play the card on an unrezzed pieced of ice.

EarthDefenseForce said:

The fact that the card doesn't specify a "rezzed" piece of ICE means that, if it's installed, he can use this card to affect it.

That honestly seems like a waste of the card, unless it can't be played in the middle of a run. It can, can't it?

EarthDefenseForce said:

Of course not. Playing an event requires an action (click). You can't take an action (like playing an event) while resolving another action (making a run).

EarthDefenseForce said:

Can't be played in the middle of a run.

Not necessarily a waste. What if you know , for a fact, you can get through all of the already rezzed ice on a server, and have credits left over, but you're not sure what type that new one is… maybe it's a "trap" ice… maybe it's a "sentry," and you don't have that breaker out yet… this card helps you by eliminating the strategy the corp might have had in putting down an ice you can't break by turning it into one that you can.