I'm sure you don't need to portforward for GTA unless you are using some strange mod.
unless you have a game that portforwards itself (there isn't one), you will need to portforward unless you have a really loving laid-back router
or some other weird circumstances
I never had to portforward for BL, but hosting any other game has proven near-impossible
also you don't have to if you enable UPnP, which most games have by default (though there may be a setting, like in BL)