Some of the limitations are obvious, like limited choice of look and only 5 hours per month free playing time, then being switch to observer mode on login and from time to time. There are additional limitations on servers: only one pm per minute, no mass PMs or PMs to other servers, limited choice of classes and weapons on Zone, you cannot become staff on servers.
limitfreeplayers2 is disabling bombs, horses and projectiles for trial accounts and should not be used except there is some hacker problem or so, although I've not heard of any such attempt for years.
Btw: thanks for my spectacular aura
