Ok to stop anymore 'How can i play it' 'What can i do' etc posts.
Website: www.knightonlineworld.com
Download it and try it.It's FREE so your not losing anything are you??
There is an option to buy in-game item's//premium service which helps considerably with Logging in//more xp/gold etc but it isnt needed(Although at certain times(GMT 09:00-21:00 it is harder to log)(roughly)).
If you want to go far then it can be a grind(unless you know people in-game)(or will spend $$ on the game buying items from people).
My opinion on the servers:
Ares:- Oldest server,not worth starting there unless you know people
Diez:- 2nd server,same as above
Beramus:- First server to see mass dupage//mass bug abuse
Cypher:- DON'T DO IT
Xigenon:- Don't know too much about this one tbh
Olympia,Edana,Manes,Pathos:- Good choices,there quieter because people have gone to newer server's or back to there original servers.Although you may struggle to find English speakers on these.
Logos,Ronark:- Newest servers but beyond help already(traditionally all the heavyweight dupers/bug abusers go to the new servers to make $$).