I'm going to rate it after you fix the following bugs:
Despite the age you play in, you can still research nuclear submarines and Future Force Warrior.
Also, the nuclear submarine is awesome and all but isn't it a little over powered? It has an unbelievable range and can kill anything with 2-3 hits. Actually, 1-2 hits.
If anything, make it super expensive. Researching and building it is very cheap. Should be about 3x more expensive than a conventional nuke.