The unmeasured echo
A Breach is the unmeasured echo of an incursion. There are nine, one anchored to each incursion in the arc. What was never recorded does not obey the record.
Inside, the physics differ
The arenas are impossible by design: two incompatible themes occupy the same room. In the third incursion, heaven and hell. In the fourth, ice with lava. The contradiction is the point, not an art oversight.
The run, the risk and the currency that stays
The Expedition happens inside: a real-time run on a branching track, with modifiers that help and modifiers that hinder. The debuffs were required — a roguelite without risk is a corridor. The currency earned there never leaves, and the fiction carries it: breach matter does not survive outside the breach. One free run per day; extras capped per week.