For those using (or interested in trying) the #horizons IRC channel, the host name has been changed.
Old server: irc.stratics.com
New server: irc.gamers-irc.org
Old and new channel: #horizons
Apparently, Stratics has had a change of management and decided to cut ties with the IRC network running under their name. Same people, same servers, same services database, just a different domain name.
The blog at http://www.gamers-irc.org/ sums it up.
Looking for a client? Here are a two for Windows that don't cost money:
HexChat
Pidgin
Pidgin is actually a multi-protocol instant-messaging client, so if you have a bunch of messenger applications open and want to consolidate them (with no ads!), this is definitely worth looking at. Although, Google Hangouts and Skype are not supported by Pidgin at this time.
HexChat is a dedicated IRC client that has a richer feature set (and cleaner interface for IRC chats) than Pidgin.
Of course, there are other clients out there, and just as many lists of IRC clients.