KAG Netcode/Lag Compensation

No, he's just talking from assumptions that he's made based on what he sees.

There's an "unlagging" system which keeps about 2 seconds of previous network information from all players so that it can be used to reference where people were in relation to each other at a certain point in time, and therefore whether someone was able to hit someone with the positions at their respective ping. This causes the occasional "OH GOD MY 1000M SOWRD HAXKX" moments but makes sure that hitting "feels" acceptable most of the time. If you've got a huge ping then melee combat gets dicey for sure, but you can adjust for it easily enough, and archer in particular syncs out very well.
This system is based on something that was developed for early quake servers, and it basically gives laggers a chance.

There's also been a lot of work put into minimising the amount of data sent per player which helps us keep bandwidth use low while sending network information at a fairly high frequency.

We trust the client a lot more than a few other games I know about the networking behind, because we take a hard line on hacking - any video validated report nets that person a ban. We also have a guy working on specific anti-hack technology that will help us justify looking the other way a little more ;)

There are ways to make sure everything syncs 100% accurately and that everything the player is seeing is correct, but they mean latency _cannot_ be adjusted for, which means laggy players have input lag. If you serverside everything but have client-side prediction of what's gonna happen, then you have "rubber-banding", where players snap backwards if they failed to make some jump serverside. If you clientside everything then you get teleporting and all sorts of hacks are possible. We have a mix of clientside/serverside so that things are responsive enough and theres no rubber banding, but there's still some "interesting" teleportation and desync when people are moving at radical speeds or jumping off other players.

@Ardi: The reason we dont have that stuff clientsided is that it causes mad teleporting (client sends deltas that disagree with server deltas by some margin) and requires a lot of validation serverside. Same for knock-back from slashes etc, while it feels more responsive for one player, its very confusing for the other 5 or so directly involved.

 

No worries, glad I found the time to write that up as the details of implementation aren't exactly clear on inspection. I linked Michal to this thread, he's glad to hear the netcode get some praise, haha.

 

Not sure, I haven't seen the underlying code for that :)

@jeffey: Yes, and it couldn't cope with the huge ping people were trying to play the game with, haha. Rubber banding etc was very common, probably in part due to how quickly the code was thrown together ;)