Good catch on the effect, slightly off on the cause — it's not their HP, it's range. Snails are non-aggressive; hitting one lets it chase you only while you stay inside its hit-aggro range, and the knockback from repeated hits pushes you apart until that range is lost, at which point it walks back to its spawn point. That's the authentic v83 behavior for non-aggressive mobs (there's no HP-based flee logic in the mob AI at all), not a health-triggered retreat. Won't-fix, but it was a reasonable thing to suspect.

Correction — reopening this, you were onto something real.

I closed it saying the snails were just losing track of you at range and walking home, and that this was authentic. The actual problem is bigger than the symptom you described: our monster AI doesn't behave the way the real game's does. Rather than the authentic wander/chase behaviour, ours effectively sticks to the player, and what you saw was that going wrong at the edges.

So your instinct that something was off with how they were reacting was correct — I just mis-explained the mechanism and closed it too early. It's now confirmed and being worked on. Thanks for pushing on it.

Fixed and pushed. Your report turned out to be the visible edge of a much bigger problem with how monsters move.

Two things were wrong. First, we had invented a rule where hitting a peaceful monster made it chase you — that isn't in the real game at all. Aggression is a flag in the monster data, and Snails, Blue Snails, Pigs and Orange Mushrooms don't have it. They should never pursue you, hit or not. Second, and this is the 'glue' the owner described: our monsters re-aimed at you every single frame, sixty times a second, so they tracked you perfectly and could never overshoot. The real game decides a direction roughly every 1.6 seconds and then COMMITS to it, choosing evenly between standing still, walking left, and walking right.

Both are fixed. Monsters that are genuinely aggressive still chase you exactly as before.

To re-test: hit a snail a few times — it should get knocked back and then wander off in its own direction rather than locking on to you. It should feel less like it's glued to you and more like it's wandering. Do tell me if it now feels too aimless.

Follow-up — two more things landed on this after the owner pushed on it, both about how the monsters actually FEEL rather than the aggro rule itself.

First, the pacing. The original game decides a monster's next move on a timer, but it also waits for the current walk animation to finish before acting on it — so the monster completes its stride instead of snapping around mid-step. I'd only ported the timer. Adding the animation half changes the real interval measurably: a Snail's walk cycle is 900ms, so its decisions land every 1800ms rather than 1608ms; a Pig's is 500ms, so 2000ms. They should look less twitchy now.

Second, and this one was a genuine bug you'd have hit eventually: an aggressive monster chasing you had no stopping condition. It walked straight THROUGH you, then realised you were now behind it and turned around — back and forth across you forever. It now stops once it's actually touching you and stands there facing you, still doing contact damage, which is what a monster pressed up against you looks like in the real game.

To re-test: peaceful monsters (snails, pigs, mushrooms) should wander and never follow you. An aggressive one should walk up to you and STAY there rather than sliding past and pivoting. If the wandering now feels too slow or too aimless, say so — that's a feel judgement and I can't make it from here.

Fixed and shipped, and "not sure intended" was the right instinct — it was not.

Our hit-aggro was invented. v83 marks an aggressive monster with info/firstAttack in Mob.wz, and that node is ABSENT on Snail, Blue Snail, Pig and Orange Mushroom — they are not supposed to chase you at all. On top of that we recomputed a chase target every frame with an unbounded anchor search, and gave any monster you had hit a fabricated doubled detection window of 520px.

The real client re-decides at most once per 201 physics steps (about 1.6 seconds) and then COMMITS to that direction, choosing uniformly between stand / left / right (HeavenClient Mob.cpp:276-321, byte-identical in maplestory-wasm). Hit-aggro and the widened window are gone and that committed cadence is ported. Monsters that DO carry firstAttack still chase you.

So low-HP snails wandering off is now what you should see. LIVE on the published build.