Nuclear War (New World Computing, 1990)

Trick for unlimited Mega-Cannons and upgrading NP-1 Bomber from 
50 Megatons to 100 Megatons payload:

You need two things:
- 1 NP-1 Bomber
- 1 Warhead 100 Megatons

Fill the bomber, then click on the warhead. A message appears: 
"You must first deploy a delivery system!" Ignore this message 
and click on "Nuclear War". When the battlefield reappears, you 
will have gained several Mega-Cannons and the bomber can now be 
filled with 100 Megatons. You can repeat this as often as you want.

Alternative method: First select a 50 MT Bomber from the bomber 
menu and just before the start of the new round, quickly select 
a 100 MT warhead. If both were available at that time, you will 
have unlimited MEGA CANNONS in the next round and the bomber will 
have transformed into a MT-100.