There is a lot more to stable and synchronised network code than simply sending player inputs to each PC when they change.
You most likely will find that even if you have a LAN and are using identical PCs that your game diverges on both machines. Once the game becomes unsynchronised the simulation will usually become completely different on both machines in a short space of time. This is a bad thing (in 99% of cases - if you don't care that both players will have a different experience then I guess not always).
Assuming you are creating a real time game not a turn based one then this will be a big problem.
There are many articles on the internet about coding multiplayer games which you may be able to find, a few on gamasutra and on gamedev.net.
If you are doing an action game which has only a small number of 'characters' (such as in a game like Quake 3) then it is far easier to write network code. Usually this will involve having one PC acting as the 'server' which basically tells all the other PCs (clients) what the correct state of the world is on a regular basis.
If you are doing an RTS or other game with multitudes of units then a different approach is needed. There is an article on gamasutra about this using the example of Age of Empires.
You most likely will find that even if you have a LAN and are using identical PCs that your game diverges on both machines. Once the game becomes unsynchronised the simulation will usually become completely different on both machines in a short space of time. This is a bad thing (in 99% of cases - if you don't care that both players will have a different experience then I guess not always).
Assuming you are creating a real time game not a turn based one then this will be a big problem.
There are many articles on the internet about coding multiplayer games which you may be able to find, a few on gamasutra and on gamedev.net.
If you are doing an action game which has only a small number of 'characters' (such as in a game like Quake 3) then it is far easier to write network code. Usually this will involve having one PC acting as the 'server' which basically tells all the other PCs (clients) what the correct state of the world is on a regular basis.
If you are doing an RTS or other game with multitudes of units then a different approach is needed. There is an article on gamasutra about this using the example of Age of Empires.