Introversion

Is it possible to make a mod to add new victory conditions so that wiping out all enemy ships, planes, radar stations, airfields, silos, and inbound nukes starts up the Victory Timer?

Sure, all you need is access to the source.

How do I access and edit the source?

You need to travel back in time and buy the Humble Introversion Bundle.

If you know C++ I can help you access the source, if you don't , there is no point.

Well actually I know of one way to achieve a military victory: Instead the game ending via victory timer, all one has to do is program the maximum real time for several hours or use office mode. After a player wipes out all of his enemy's ability to deliver nukes in any way and the player has the highest score, then he or she can just wait until the countdown expires... though patience would be vital in this case especially in office mode as the speed is stuck at real time. In fact use of office mode is best not used in this case.

Would'nt decreasing the number of nukes needed to start the countdown work? If you choose the correct value.

Setting the max real time countdown before gameplay is another way to end the game. It just takes a bit longer.