Working of multiplayer games.

[rahul babaria]

Dear Team,
I would be happy if you could explain to me, how internet based multiplayer games work in reference to following examples -

1)suppose a game like Resident Evil 5(Re5) or Call of Duty or Quake or Unreal tournament.
In these said games a person can act as a host and launch a game and others can join in.
2)other games online like (age of empire type graphics) MMORPG where players connect to dedicated corporate game servers.

My question is I cannot understand the Background Mechanics. Suppose a Game with Re5 or Re6 graphics is made and has extensive,maps and all,if I want everybody from the world to hook up and play on the same game, and the game has changing environment or terrain, suppose a house can be decimated etc.If I were to Host it from a single server it would tremendously strain Bandwith owing to big size(and everybody would be downloading) and all and if every player had a dvd of the game each would be a host(so multiple games not one game with all players) So is there a way that the map or terrain stays on one server and player can play on the terrain without massive upload download and still enjoy game of high graphix ?

 

[Sunius]

Graphics aren't streamed from the host. Only very little chunks of data what basically is happening is sent, and those account for around 5 KB/s bandwidth at most.

 

[HEXiT]

most online games use something called packet data, most often its sent in 4KB packets although some newer games send as much as 8KB this can be sent in 2 ways. either per second or per frame games that send it per second tend to be rts and mmo type games while per frame tend to be fps shooters. on per second games line latency is unimportant as long as it within a reasonable time of 2-3000 mili seconds.
on fps shooters it can make the difference between a hit and a miss so needs to be as small as possible. another thing s most fps games need a minimum of 30 packets per second to give smooth gameplay for all players and some games will allow you to send as many packets as you have fps which in some games can become a huge advantage if you have a pc that gives you more fps than any 1 else.
although this has changed somewhat over time with a lot of games introducing upper limits to limit said advantage and reduce player induced lag most games now like cod and battlefield will allow between 15 and 100 packets to be sent per second why so low? well 15 is about as low as you can get and still give the illusion of movement to the brain although this can induce headaches and fits in some people who suffer photo sensitive epilepsy (the lower limit is 12.5 fps for movement but anywhere between 12.5 and 22fps can induce a fit if it involves flashing images).

there is still 1 game as far as i know which allows unlimited packet data and thats the counterstrike series. as far as i know it will allow up to 333 packets which is pretty much for all intents and purposes unlimited as you would need a very very strong pc and a peerless line to give that kind of data through put.
like i say most games stick to 4KB but call of duty 4 and some later versions allow up to 8KB per frame this data includes everything you can think of from players x/y/z/d (d being direction there facing) coordinates to there weapon load outs, there health and anything else they deem fit to send. this data needs to be sent every fram so can result in a fair bit of bandwidth after an hour or 3 of gameplay so be careful if your on a data usage plan.
if your hosting the game things can become a little more complex you will often have to send as much as 32x the amount of data depending on how many players you have playing on your games server (your pc being the server) this can have 2 effects... if your pc isnt particularity good it can slow you down and impact your games fps, which in turn will reduce the amount of packets that can be sent and the end result is a laggy game for every 1 connected. the other being if your pc can handle the data through put , you will get a small but much sort after host advantage. you get an advantage because you dont have to send data down a wire so any input you make with the mouse and keyboard are near instantaneous. meaning you will see and be able to shoot the enemy from 10-250ms b4 they see you (some games allow up to 800ms of ping which is an 8th of a second which is just to much, 250 is about as high as you should allow as this will minimize lag for every 1) ... i could go on for another couple of pages but im gonna stop here as i have covered the basics... let me know if you want more info...

 

[rahul babaria]

Just one point, suppose a company is hosting a game like Re5 on its server, we has gamers , if we hook up via broad band the maps,other players etc and terrain which we see will be downloaded on our PC's HD or will it stay on the Host PC ?

most online games use something called packet data, most often its sent in 4KB packets although some newer games send as much as 8KB this can be sent in 2 ways. either per second or per frame games that send it per second tend to be rts and mmo type games while per frame tend to be fps shooters. on per second games line latency is unimportant as long as it within a reasonable time of 2-3000 mili seconds.
on fps shooters it can make the difference between a hit and a miss so needs to be as small as possible. another thing s most fps games need a minimum of 30 packets per second to give smooth gameplay for all players and some games will allow you to send as many packets as you have fps which in some games can become a huge advantage if you have a pc that gives you more fps than any 1 else.
although this has changed somewhat over time with a lot of games introducing upper limits to limit said advantage and reduce player induced lag most games now like cod and battlefield will allow between 15 and 100 packets to be sent per second why so low? well 15 is about as low as you can get and still give the illusion of movement to the brain although this can induce headaches and fits in some people who suffer photo sensitive epilepsy (the lower limit is 12.5 fps for movement but anywhere between 12.5 and 22fps can induce a fit if it involves flashing images).

there is still 1 game as far as i know which allows unlimited packet data and thats the counterstrike series. as far as i know it will allow up to 333 packets which is pretty much for all intents and purposes unlimited as you would need a very very strong pc and a peerless line to give that kind of data through put.
like i say most games stick to 4KB but call of duty 4 and some later versions allow up to 8KB per frame this data includes everything you can think of from players x/y/z/d (d being direction there facing) coordinates to there weapon load outs, there health and anything else they deem fit to send. this data needs to be sent every fram so can result in a fair bit of bandwidth after an hour or 3 of gameplay so be careful if your on a data usage plan.
if your hosting the game things can become a little more complex you will often have to send as much as 32x the amount of data depending on how many players you have playing on your games server (your pc being the server) this can have 2 effects... if your pc isnt particularity good it can slow you down and impact your games fps, which in turn will reduce the amount of packets that can be sent and the end result is a laggy game for every 1 connected. the other being if your pc can handle the data through put , you will get a small but much sort after host advantage. you get an advantage because you dont have to send data down a wire so any input you make with the mouse and keyboard are near instantaneous. meaning you will see and be able to shoot the enemy from 10-250ms b4 they see you (some games allow up to 800ms of ping which is an 8th of a second which is just to much, 250 is about as high as you should allow as this will minimize lag for every 1) ... i could go on for another couple of pages but im gonna stop here as i have covered the basics... let me know if you want more info...

 

[Sunius]

No it will not be downloaded. The only things that will be downloaded is your player coordinates, what weapons you wield (names, not graphics) and coordinates what you shoot at.