Blitzschlag: chains of one cast take separate routes

The chains of a cast share the enemies they have claimed and prefer
unclaimed ones. Each chain keeps its heading and ranks candidates by
distance and turn; a chain's first jump turns away from the directions
the other chains set out in, so they keep fanning out. Jumps reach 75 %
of the cast range.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/chain-lightning.md

@@ -53,6 +53,24 @@ ends (a lone enemy is hit once). Two enemies: it bounces between them.
   are created at the first jump targets of the other chains (copies of the
   event with [14] = N - 1); their first hop has no arc.
 
+Separate routes (2026-10-18). Request: the chains should not all follow the
+same route. Before, each chain only avoided the enemies it had hit itself, and
+only the extra chains' first targets differed. After that, parallel chains
+picked the same nearest enemies and could swap onto each other's route. Now
+the chains of one cast share a list of claimed enemies (the first target, and
+every target as soon as a chain picks it). A jump prefers an enemy no chain
+of the cast has claimed, then one this chain has not hit, then any other,
+then the current one.
+
+Follow-up (2026-10-18): "only on the first spread, then they most times merge
+together again". The nearest free enemy of two chains often lies in the same
+group. Each chain now keeps a heading (caster -> first target for the main
+chain, then the direction of its last jump), and the candidates of a tier are
+ranked by distance × (1 + 2 × turn), with turn = 0 straight ahead and 1
+straight back. A chain's first jump has no heading yet; there the turn is the
+largest closeness to the directions the cast's chains set out in, so the
+branches fan away from the main chain and from each other.
+
 First version (bolts copied for every jump, not using the game's chain)
 replaced the same day: it doubled the jumps.
 
@@ -91,3 +109,7 @@ step of the ray point).
 Follow-up (2026-10-17): jumps at 900 felt too far. The cast keeps 900; jumps
 use `JumpRange()` = half the cast range (450). The tooltip shows both
 ("Reichweite", "Sprungweite").
+
+Follow-up (2026-10-18): with several chains, half the cast range left too
+few separate targets ("maybe chain range needs to increase to 75% of cast
+range"). Jumps now reach 75 % of the cast range (675).