The UCN never commited Genocide, they let the Helghan settlers leave Vekta of their own free will, those Helghan Settlers who participated in the Exodus knew full well what they were going to when they decided to settle Helghan. The UCN was wrong to marginalize the Helghan settlers following the first Extrosolar war, but the terrorism on the part of Helghan settlers only justified further action against them. The records were very clear that if a Helghast settler chose to work with the UCN settlers in making Vekta a peaceful and prosperous region, that they ould be treated the same as any other colonist.
Only one side, currently, is planning Genoice, and it's Visari.
Visari's plan is simple:
Utilize deep-cover agent ISA General Stuart Adams to neutralize the orbital defense platforms.
Utilize deep-cover agent ISA General Dwight Stratson to gain access to intelligence and lure the ISA troops out of the cities.
Mount an invasion of Vekta whilst the orbital defense platforms are down, under the command of General Joseph Lente.
Reactivate the defense platforms in time to defend Vekta against the inevitable support fleet sent by the UCA.
Declare the system to be under Helghast control and sue for peace with the UCN whilst the UCA is still reeling from the loss of its fleet.
Use the resources of Helghan and Vekta, as well as technology captured from the wrecked
UCA Navy fleet, to build a Helghast fleet capable of defending the system from the UCA Navy.
Begin charging trade tariffs for passage through Helghast space to Earth again.
Blockade the Earth and strangle the UCN into submission.
Capture the UCN Navy shipyards and orbital defenses.
Leave Earth's population to starve to death. Build an enormous fleet and establish Helghast hegemony over all colonies.
The entire population of Earth (Billions upon Billions), add to that his goals of establishing Helghast rule over all the known galaxy.