Had fun playing Portal? Wished the gun would be available in Half-Life 2? Wish no more for Primotech has posted a guide that lets gamers take their Portal gun into the legendary shooter and have some fun. They have detailed instructions to get the gun working in the game, though it will require some technical wizardry for most of us. Also, they note some limitations of the gun, stating that NPCs cannot pass through the portals, though ammunition and other items will pass through just fine. And while it works in Deathmatch mode, other people cannot be added to the match.