I have routerOs v4.5 with hotspot useraccounts. I want a way to block network games and file sharing. Also I want a way to unblock network games and file sharing when I want , then block them again.

Blocking file sharing could be difficult, if not impossible. Many of the popular file share programs use encrypted connections over port 80... so you can't read it to see if it is file sharing, and you can't block port 80 because of http.

There is a p2p filter in the firewall that you can turn on to block known file sharing programs, though, and that could help cut back on it.

As for blocking games, if they are installed games that use known ports, just block those ports. If they are websites, you could use the transparent proxy to block all websites with the word "game" in the url, for example... but that won't block all of them.

Also, "smart" people can get around many things that you block, if they so choose.

Blocking file sharing could be difficult, if not impossible. Many of the popular file share programs use encrypted connections over port 80... so you can't read it to see if it is file sharing, and you can't block port 80 because of http.

There is a p2p filter in the firewall that you can turn on to block known file sharing programs, though, and that could help cut back on it.

As for blocking games, if they are installed games that use known ports, just block those ports. If they are websites, you could use the transparent proxy to block all websites with the word "game" in the url, for example... but that won't block all of them.

Also, "smart" people can get around many things that you block, if they so choose.

I am not talking about the internet. I am share files in LAN and games in Lan. a game between two people or more using my LAN not the internet. when the user login , he will be limited to the speed I specify for him. But for example if 8 users decide to play a network game by connecting to my AP without login to use the internet, won't this effect the internet usage of other users

Disable default-forwarding on your AP.
e.g /ip interface wireless set 0 default-forward=no