https://longturn.net/game/LT55/
Some of the stuff:
- the default diplomatic state between the nations is peace instead of war
- nuclear weapons can destroy roads, mines, city improvements...
- techs can't be stolen by conquering
- the chance to steal techs with units is not linked to the probability of regular diplomatic actions
- it is possible to lose your gold if the inciting/bribing fails
- the nuclear weapons no longer kill 50% of the citizens but instead it can be adjusted to 30% of the population
- it is possible that some units inside the cities survive the nuclear attack so that nuclear weapons are no longer a binary weapon
In addition to this tech trading (or tech stealing) no longer makes the game a popularity contest even while you can steal techs. Democracy is not necessarily the ultimate government since the other ones also have a purpose now.
This is a Freeciv 2.6 based game you can play with the standard vanilla client.