You're all crazy! Jennifer Lopez would play the best Alyx!
George Clooney... Ben Affleck... Gordon Freeman, in the same sentence? Wow, that's bizarre. You'd cast two of the most horrible actors as Half-Life's perpetual hero? Pfft.
If I were the director of the 'Half-Life' film I wouldn't quite know who I'd cast as Gordon Freeman. Hm, maybe Nic Cage? With a few adjustments, I think he could pull it off.