The history of Earth-17 remains not entirely  understood.  One theory posits that this Earth was largely similar to Earth-0 up until 1963 and the arrival of a Kryptonian spaceship headed for Kansas in the United States.  The American military falsely interpreted this event as an attack by the Soviet Union, and launched their full nuclear arsenal which provoked an equivalent response from the Soviets.  In the resultant cataclysm, a large amount of Earth's population was slain.  The spaceship was also evidently destroyed as no Kryptonians are known in this timeline.  In the aftermath, small pockets of surviving humanity struggled to restore the Earth while other humans were radically mutated, becoming monstrous competitors for Earth's dominant race (Infinite Crisis: Fight for the Multiverse Game). 

Three aspects of Earth-17 have been described at least superficially:

1 - In the immediate aftermath of the war, there may have been a series of smaller wars between surviving groups of humanity.  One was called the "Hydrogen War" in 1986 leading to further degradation of humanity.  In this time frame, a group of former soldiers and adventurers bound together after being targeted by a warlord known as the Black Baron.  The group, let by Gardner Grayle, crafted radiation proof armor and worked for peace and restoration on  the backs of huge dalmations at the Atomic Knights (Strange Adventure #117).

2 - At some point after the war, a version of Starman clad in the classic uniform of the Starman of Earth-Two, Earth-0 and Earth-22 appeared.  This Starman was a large gorilla armed with a cosmic rod.  This Starman was captured by Monarch during the Arena event and slain by the Starman of Earth-48 (Countdown:Arena LS).  As that event almost immediately faded from reality, it is likely this Starman still lives on Earth-17.  How this version came into being is unknown.  One speculation would be that the Justice Society was killed in the nuclear holocaust of 1963 and  their equipment found by a society of sentient apes who assumed their identities and heroic mission,  This is speculation is not evidenced beyond the existence of a primate Starman however.  Whether Earth-17 has had contact with other Earths in the past is also speculative.

3 - Finally, it is known 50 years after the war, there is grinding progress toward civilization.  Some cities have been rebuilt and a new generation of heroes has emerged, styling themselves as the Atomic Knight of Justice after the historic group.  Led by Captain Adam Strange, the group seeks the Cosmic Grail of Earth-15 which the believe will shield their world from Darkseid (Multiversity Guidebook #1).  Prominent on the team is the Batman of Earth-17 who is Bruce Wayne of the East Gotham Rad-Pit.  Batman has been the primary ambassador who becomes of a member of the multiversal Justice Incarnate (Multiversity #2).