What does the ice do if the runner has no icebreakers?

Ends the run unless the runner is untagged. The amount of times the runner could get through Pachinko equals their clicks per turn - tags, spending the actions and credits to remove them.

What cost does it represent against icebreakers?

As a 5-strength barrier with two subroutines, this will cost 4 to 6 credits for most fracters to break, except for Morning Star (1 credit), BlacKat (3 credits, 2 of which come from stealth sources), Inti (10 credits), Spike (4 other icebreakers installed and Self-Trash) and Cerberus "Lady" H1 (2 credits and 1 power counter). It is unlikely that Spike will have the necessary strength to break Pachinko, and even then, they will need to trash it to get through once, which ends up being favourable to you due to the 1 rez cost. The Runner should have no issue spending the power counter and credits on Lady. Against Anarch, this is susceptible to D4v1d, but the runner won’t be happy to spend two of the three counters on breaking a 1-cost ice.

In terms of AI breakers, it will take most of them 6 to 9 credits for them to break it, except for:

Crypsis (7 credit and a click)

Faust (8 cards from the Runner’s grip)

Knight (4 credits and a click)

Overmind (5 credits and 2 power counters)

Pachinko seems to have very favourable numbers, sitting at an impressive 5-strength for the low price of 1 credit to rez. In this regard, it will drain the Runner of their economy fast, so it ideally wants to be positioned in a central server the runner wants to visit often, such as r&d or hq. The strength of Pachinko lies in having the runner go through it several times a turn. And obviously, the runner needs to be tagged, otherwise, this card does nothing.

Does the ice have any special properties?

No.

Does the ice have any particular synergies to consider?

In terms of synergies for Pachinko, look for cheap and reliable ways to keep the Runner tagged, with a focus on reliability. Consider the following cards:

Data Raven, is probably the most secure tagging card in the game. Works especially well if it's slotted before the Pachinko, although some NBN strategies prefer to devote the Data Raven to remote servers. Consider building a remote server with a Pachinko behind a Data Raven, but be prepared for the Runner to eventually build the necessary economy to get through.

Gutenberg, Data Raven’s poor brother, is a good choice if you feel like you’re running a bit short on credits, or that you’re being assaulted too early, although it would only feel somewhat right if it’s before the Pachinko with both defending R&D. Otherwise, understand that in the late game, the trace won’t ever fire.

ChiLo City Grid, to tag the Runner as long as a trace is successful. It is somewhat feasible for your non-end the run ice in NBN to have traces that maybe are too high to pay up or feel unimportant, even outside faction something like a Caduceus, which has a first unthreatening subroutine, can lead to the Runner taking an unexpected tag. Be ready to build ice that traces before Pachinko so you can ensure the runner is tagged by the time they reach the end of the server.

Dedicated Response Team, as it deeply cares about the runner being tagged, which Pachinko ensures, and is a great ambush tactic for after breaking Pachinko, since it can be pricey to break. If you plan on the Runner being tagged when they run into Pachinko during a run into centrals, you can probably get triggers from Dedicated Response Team.

Bandwidth, as it’s an extremely cheap piece of ice which combos well in cost with Pachinko. It’s unlikely that even if they have the tools to break a 5-strength barrier, they will also have the tools to break a 5-strength code gate. Remind yourself that if they do break the bandwidth the pachinko is useless, so use it with precaution and only to turn your Pachinko into a real barrier for the early part of the game.

Big Brother, to make tags stickier. Other cards will take greater advantage of it, but Pachinko does get better if you can make sure they can not normally take out all of their tags and run in the same turn. In this regard, SYNC: Everything, Everywhere is probably the identity that can make Tags even harder to remove, since it makes tag removal pricier on top of the pricier nature of Pachinko.

Does this ice go into any particular deck?

Weirdly enough, for all the prior praises, no decklist on the db has Pachinko in. This is probably because it can be a bit unreliable and there are not that very many advantages to playing tag spam in a way that cares about whether the runner is tagged or not. I think it’s very harsh to dismiss this as useless, probably could find a home as a 2-off on something like SYNC: Everything, Everywhere or covering centrals on a version of Near-Earth Hub: Broadcast Center with DRT which takes advantage of tags.

Could you slot this ice outside of its faction of origin?

NBN is the only faction that can get the runner to be reliably tagged during a run to get the most out of Pachinko, therefore it’s pretty hard for it to be seeing any particular use out of yellow. If anything, Weyland can afford to pair it with cheap tracers such as Shadow or Salvage, but Weyland’s interest in tagging the runner lies in different directions than ending the run, focusing instead on blasting damage on the runner.