Speculation: According to HSD2.0p.31 the credit was crashing, and only Marsco and its subsidiaries had any actual resources. The Big Three start to squabble over resources and no longer cooperate. At the worst of this period, the shadow war between vectors and humanity reaches a turning point, disease cripples society, and Pulse decides that blood sports are a pretty good idea. This suggests a dark period with weak leadership and questions about day-to-day survival.
Finances in Sol are a juggling act between MarsCo and ASR, shuffling resources to patch up holes. Little or no budget for nonessential research, and progress in many ways grinds to a halt.
The general arc of this period is: The credit system is unstable, creating financial crisis. MarsCo is forced to spend its resources on infrastructure and dealing with the fallout of the Big Three subsidiaries leaving its umbrella, taking resources and talent with them…particularly hobbled by early ASR’s crippling of their AI. The Big Three pursue projects that ultimately are in their own interest, leaving the primary infrastructure. Some positive happens when Marsco allows ASR to “repair” its AI, but plague and economic hardship continue, and no corporations beyond Marsco and the Big Three have any meaningful resources. Scientific advancement grinds to a halt.
The Shadow War is a portion of the backdrop of this, though in this version the Big Three are primarily vector-owned and the humans primarily run Marsco, so one battleground of the Shadow War is the subsidiaries cannibalizing Marsco while maintaining something like society.
A few factors combine to end the 100 Years Recession: The end of the shadow war (the remaining human race exiled to Terra), the positive energy of “life on terra” generally (compare to the energy of the moon landing, Earth 1969), and most importantly, the success of the Ledger in unlocking resources…and again pulling resources away from Humanity.
Three major factors end the recession: