right now the game itself is having problems, the game is inaccesible becuase the server is down nobody, configured ports or not, can enter right now
so just wait a lil til the server gets back up (timeframe differs evertime)
you need ports open in order to "host" your own games hosting means setting up your own game and waiting for others to join, without configured ports "or alloy" you cant host, if your ports arent configured properly you can still join any game hosted by others tough
so no, you do not need your ports configured to play online, you only need them if you want to make your own games
if the game says you are disconnected from ICO the problems lies with ICO, there have been alot of problems with the server latly, so dont worry about that (or do.. actualy.. it should've been by fixed now)