Combat mechanic — not covered elsewhere

Melee Line of Sight

If you cannot reach it, it cannot reach you — the same wall-check runs in both directions

Standing on the far side of a wall from something dangerous is supposed to mean something. In Blister Online it genuinely does: every melee attack — yours, and every creature's bite — draws a straight line to its target before the hit is allowed to land, and if anything solid sits along that line, the attack is refused instead. The design notes call this "the same predicate in the same direction": it's one shared check, reused for both sides of a fight, so the rule can't quietly mean different things depending on who's swinging.

Built to answer the same question both ways

The rule started as a fix for the player's own reach — an earlier build let you swing through your own walls at something standing outside them, which made a house's walls decorative rather than protective. The fix was extended to creatures immediately afterward, on the reasoning that once creatures could physically collide with built pieces (they walk into a wall like anything else), they'd otherwise just walk up to it and bite through it anyway — "that is the whole point of a house," as the build's own notes put it. Both directions run through the identical function, checking the identical straight segment between one point and the other, so a wall that blocks your swing is guaranteed to block the same creature's bite back at you.

Refusing a hit still spends the attacker's cooldown either way — a creature blocked by a wall swings and misses rather than quietly banking a free hit for the moment you step around the corner.

Two separate questions: can it reach you, and is anything in the way

A bite has to pass two independent tests before it lands. First, plain reach: the attacker's own attack range, plus a small margin, and a vertical gap of under 5 units between your feet and the creature — a creature standing on a ledge far above or below you can't hit you no matter how close it looks on the map. Only once both of those pass does the game bother asking the second question: is there a straight, unbroken line between the two of you at all. A creature that's out of range or too far above or below you never even reaches the line-of-sight check in the first place.

What actually counts as "in the way"

For a long stretch, only one category of solid was ever checked: pieces from the Build Tool — your own walls, floors, and doors. That meant the rule worked perfectly inside a house you built yourself, and not at all inside the game's own pre-built structures: a stone chapel or a town wall was completely invisible to the check, so a creature on the far side of one could still bite straight through it. The fix asks the world's own buildings and terrain first, specifically because — in the fix's own words — "there is stone everywhere and most players have built nothing," making it the far more common case than a player-made wall. Only if the world itself doesn't block the line does the check fall back to asking about your own placed pieces, exactly as the original rule always did.

This closes the damage half of a much bigger gap, and deliberately not the other half: a creature's movement still ignores buildings entirely. It can still walk straight through a wall and end up standing inside a building with you — what it can no longer do is reach a hand through that same wall from the outside and hurt you without ever entering. Making creatures actually respect walls while moving is a separate, much larger change, and is written up as its own future project rather than folded quietly into this one.

One kind of forced movement was fixed earlier and separately, though: knockback. Landing a hit used to be able to physically shove a creature straight through one of your own placed walls — not by the creature walking, but by the hit-reaction system pushing its position directly, several times a second, for a short stretch after every landed blow. Fighting anything next to your own walls could punch it clean to the other side. Knockback is now stopped by the same walls a normal step is, and clears its own leftover push the instant it makes contact, rather than pressing uselessly against the wall for the rest of its duration (which used to read as the creature vibrating in place).

Three rules that had to be exactly right

Standing inside a solid can't make you invincible. A player can genuinely end up with their own eye position inside a registered solid's box, so the check has to fail open rather than treat that as an automatic block — verified directly by standing inside a building's own body and confirming a creature beside you in that same room can still reach you.
A doorway has to stay genuinely open. The check respects the same door gap described on the Building page — line up with the opening and the line of sight passes clean through, even though the wall on either side of it still blocks.
The search has to look in every chunk a building actually touches, not just the one its centre point is filed under. A structure large enough to span more than one map chunk was, for a moment during development, invisible to a line of sight crossing only its far half — caught by testing the doorway rule against a real building rather than assuming the math was already right.

The same rule protects your companions too

The check isn't limited to the player. A summoned ally and your own spouse — see Marriage — fight at melee range using the identical predicate: a pet or a spouse reaching through your own wall to hit something standing outside it is treated as the same kind of exploit as a creature reaching in, just aimed the other way. One shared question answers "can this attacker reach this target," and every kind of attacker in the game asks it the same way.

Version history

The player's own swing gets a wall check. Closed the exploit of hitting something through your own placed walls.
Creatures get the identical check for their bite, closed the moment creatures started colliding with built pieces and could otherwise walk up to a wall and eat through it.
Companions (a summon, a spouse) fight through the same predicate, closing the same exploit from the other direction — a pet or a spouse reaching out through your own wall.
The game's own pre-built structures finally checked, not just player-placed pieces. Before this, only a house you built yourself actually blocked a bite — a stone chapel or town wall did nothing, because the check had never been taught to ask about the world's own buildings at all.

Trivia

The chunk-padding rule above was found by testing the doorway rule against a real building and getting a result with no sane explanation, not by reading the collision code and spotting the gap — the bug only became visible once someone actually asked the question a player would.
This entire check can be measured directly at a wall with a real creature, without ever needing to actually throw a punch — useful because the swing input itself is mouse-only and can't be triggered by an automated test; only the decision of whether the bite would land can be.