A party split turns one boss arena into parallel spaces. Here four living players divide 2+2, complete different left and right objectives, and reopen a shared gate only after both tasks finish. The mechanic is not merely standing far apart: each side has independent progress and the slower side controls the whole group's release.

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Reveal and divideAt 0.65 seconds Kern marks two distinct lanes. Four players travel in assigned pairs, with their whole bodies clear of the central divider by 1.70 seconds.
Split Kern's arena, finish both tasks, reunite Kern separates four players into two lanes with a central divider. The left pair completes a crystal first; the right pair completes a lever later. Each side has its own progress bar. Only after both complete does the shared gate open, and the players reunite below the divider. III Boss Player

At 0.65 seconds Kern marks two distinct lanes. Four players travel in assigned pairs, with their whole bodies clear of the central divider by 1.70 seconds.

Implementation checklist

Define assignment, full-body divider clearance, two independent completion events, a shared deadline, gate logic, reunion, and reset.

Core checks

Three questions for the mechanic

  • What counts as a valid split?

    Snapshot four distinct living players and assign exactly two to each side. At separation, include each player's 24-unit body radius when checking the central divider; a center on the correct side is insufficient. Lock the roster through the task window so a disconnect or duplicate ID does not silently satisfy both sides.

  • What must each side do?

    Give the left and right sides separate objectives and completion events. In the demo, left finishes at 2.60 seconds and right at 3.25. Keep both progress signals visible; do not substitute one aggregate bar, because players must know which side is holding the gate. Test both completion orders and a side that never finishes.

  • When does the gate open?

    Open the shared gate exactly once after both valid sides finish before 3.60 seconds. A missing player, divider overlap, late task, or duplicate callback must not produce a second opening. Reserve a separate reunion route and log assignments, each task event, gate event ID, deadline result, and reset.

Design mistakes

  • Calling a spread a split

    Distance alone does not create parallel work. Both sides need distinct, visible tasks whose completion affects the same gate.

  • Hiding the slower team's progress

    If the faster side finishes and sees only a locked gate, waiting feels arbitrary. Show each side's completion state and the remaining deadline.

Tuning

Tune the attack

  • Make lanes readable without color

    Use a physical divider, separate objective shapes, Roman I and II labels, and two progress bars. Hue reinforces the split but cannot be its sole signal.

  • Budget the slowest route

    Measure travel to both lanes, objective interaction, and movement back to the gate at ordinary speed. A group should fail because a task was missed, not because the path is geometrically impossible.

  • Keep completion atomic

    Record an encounter ID and per-side completion times. Resolve the shared gate once after checking both, then reject duplicate callbacks and clear only encounter-local state on retry.

Arena

  • Two runes, one sealed passage

    Kern raises a stone wall through the arena. One pair charges a crystal, the other pulls a rune lever; the lower gate lifts only when both circuits answer.

Player upgrades

  • Vary tasks without losing the dependency

    The sides may defeat different enemies, hold switches, or solve asymmetric hazards. You can add a third room, but then recalculate roster size, independent progress, and reunion timing. Preserve the common dependency: no side alone can release the whole group.

Do not confuse this with

  • Parallel objectives, not pair composition

    Pairing polarity checks who shares a receiving zone at one pulse. Party split checks whether separated teams complete distinct objectives before a shared release. Stack damage asks several players to overlap; here the two teams cannot occupy the same lane while working.

Bosses that use this mechanic

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