Two amoral scientists or salesmen arm primitive worlds for entertainment

Question

I read this about 2003, in a library book so it's hard to say how old it was. The 1990s at the latest.

There were two advanced space travellers - they may have been scientists or salesmen, or both. They were bored and as a form of entertainment they gave or sold two opposing planets advanced (most likely nuclear) weapons to see how long it would take for them to obliterate each other/themselves.

They were acting alone, not for any governments.

There was a line from one to the other like:

Shall we play war?

or

Shall we play extinction?

or

Let's have a game of extinction/war/obliteration

Something along those lines.

I never actually got to the finish so no info on conclusion.

Answer 1

It just might be "The Rival Rigelians" by Mack Reynolds (1968). At one point there's a sort of 'wager' on which civilization is going to blow itself up first.

From one of the blurbs:

The team from Earth had the task of raising backward planets to the home world's high level. The situation on Rigel was this:

"The most advanced culture on Rigel's first planet is to be compared to the Italian cities during Europe's feudalistic yeas. The most advanced of the second planet is comparable to the Aztecs at the time of the Spanish conquest."

"These planets are in your control to the extent that no small group has ever dominated millions before. No Caesar ever exerted the power that will be in your collective hands. For half a century, you will be as gods and goddesses!"

But the Rigelians were themselves descended from the lost colonists of old Earth and they could learn their lessons as fast as they could be taught.

In fact, they could even teach their teachers a thing or two. And therein lay the peril the professors from space never dreamed of.