This is the proposed follow-up story that may begin production once the Rachni/Krogan Arc (TCE and TKR) has concluded.
None, as of the moment. Expect the traditional rules that our writers must abide for collaborations.
In 2182 CE, the geth have funded an Alliance Major's rebellion and takeover of the uranium rich colony of Vivacta triggering the Vivactan Campaigns. The dictator, A Mr. Debec took over much of the colony leaving one province left standing.
The Alliance rushed in to aid the colony backing it with financial and military aid. Debec launched a proxy war hiring terrorists and mercenaries to cause havoc for the Alliance while in secret Marine Recon forces sabotaged Debec's nukes in the mountains and the STG prowled the desert for caches of nukes, something which also drew in Red Legion.
Eventually war broke out leaving countless dead and Debec captured. However with the geth's puppetmaster plan in ruins they invaded the planet themselves taking massive losses and inflicting millions of deaths before being driven off world.