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Comment by armchairhacker | Hacker News Reader

Is rollback netcode and prediction really that good that people enjoy playing realtime multiplayer without worrying about latency?

20ms is considered really good ping, but humans can react faster than 20ms. Yet even fighting games are played online. I get that they have good netcode but how does that work?

Meanwhile LAN or an actual wire across systems means almost no ping, and almost no penalty for transmitting extra data. If you wanted you could potentially even use memory-mapped I/O (although that's probably a bad idea). No more complex workarounds required to simulate realtime interaction among distant systems.

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In fighting games we still have to worry about _network_ latency, as high ping will cause frequent rollbacks. A more accurate way to think about it is that rollback netcode enables very low _input_ latency which makes online feel more like offline, compared to previous implementations that literally delayed controller input while playing online.

Humans cannot react to anything in 20ms, it's closer to 200ms. We consider a move faster than about 18 frames to be effectively unreactable in the heat of gameplay. At 60 FPS that is 300ms.

This depends on the game, a bit. I believe you are talking about reacting to unplanned events. For some games, such as beat-matching ones, where players might have patterns memorized, smaller latencies matter. I remember working on PS game, where Sony requested that we poll input faster than our 60Hz refresh rate so we could apply special "super accurate" bonuses for players that could hit things within such tiny thresholds.

Apparently in Japan where such games are especially popular (or were at the time), players really do appreciate such razor-thin input timing margins.

Yes rollback really is that good. Guilty Gear Strive is an excellent example of it.

Why are you ignore the obvious issue of distance? LANs are great, you just have to be next to each other don't you, which is kind of a HUGE problem.

You can probably do memory mapped I/O if you use a modern cable and hardware like Thunderbolt.

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