Stridergate

The entry point formed when the Exostrider and the Threnodian Aleph-1 entered Solaris. The overlying Soliskin root network holds Aleph-1's power at bay, the "sealed doors" of the Stridergate.
The Keystone is the "lock" that keeps the Stridergate closed.
Beyond it may lie the "universe" that Solaris has always longed to explore.