iptables vs. game

[MirekO]

I'am preparing to use iptables. I read documentations, manuals, howto's but
still hav'nt
answers for
1/ what internet games will work throught the iptables NAT?
2/ what internet games will NEVER wokr throught iptables NAT ?
3/ what internet games need additional moduls to work ?
4/ some example of iptables rules, that make internet games work ?