Grottoes · How it works

A treasure map = a quality (2 to 248) and a seed (0 to 32,767). Everything follows from them. The tools on the Grottoes page redo the game's exact calculations: decode a name, find your map with its floors and chests, predict the next map.

A new map's quality

• Base, when the map comes from the open grotto's boss: the hero's highest level in any vocation (99 at most) + 5 × the most revocations in one vocation (10 at most) + that grotto's level.
• For a map drawn at random elsewhere (reward): highest level × 1.5 + 5 × revocations, rounded down.
• Variation: with d = base ÷ 10 rounded down, the quality ranges from base − d to base + d − 1; base + d is only possible when the base is a multiple of 10. Every value is equally likely, except the base itself, twice as likely when it is not a multiple of 10. Then clamped to 2-248.
• The variation, the seed and the entrance location all come from a single number from 0 to 65,535, read from a console counter: 65,536 possible maps for a given base. As a result, 302 seeds never come up, and a given map can only come from certain bases (the tool lists them).
• Entrance location: drawn among nos. 1 to 47 if the quality is 50 or less, 1 to 131 from 51 to 80, 1 to 150 above (table of the 150 locations). Each location has its own treasure map drawing: the world map on the Grottoes page, put together from the game's region maps (each region in its place in the world, as the Starflight Express computes it), places the 150 entrances and shows the 150 drawings.

What the quality, then the seed, decide

• Only the quality band matters (12 ranks: “By map quality” table (below)): same seed and same rank = same grotto.
• The rank sets the ranges; the seed draws within them: environment (cave 30%, ruins 40%, ice, water, fire 10% each), floor count, first-floor monster rank, boss (weighted draw: the strongest are rarer).
• Level = 3 × (floors + first-floor monster rank + boss no. − 4), plus a draw from −5 to +5, clamped to 1-99. Possible levels by rank: “By map quality” table (below).
• Name = material (from the monster rank) + place (from the floors and environment) + suffix (from the boss): this is what the “Decode my map” tool reads.

Inside the grotto

• Square floors: 10 to 14 tiles on floors 1-4, 12 to 15 on floors 5-8, 14 to 16 on floors 9-12, 16 below.
• Monster rank + 1 every 4 floors. The boss floor comes after the last floor, with no wandering monsters.
• Chests: none on floors 1 and 2 nor on the boss floor; 1 to 3 from floor 3 on. Their position and rank never change for a given map.
• A chest's contents: drawn when the game places the floor's chests, from the seed, the floor and the number of seconds elapsed since the save or the quicksave was loaded (the community's “chest timer”: yabd.org's “Chest Timer” tool, explained on video in French by Sylwer; here: “My grotto in detail” tool). The game places them on arriving at the floor, and again on leaving a menu that covers both screens (SELECT → Battle Records); that menu does not reset the counter. Hence the trick: load the quicksave (the counter starts), open Battle Records, and leave it during the wanted second; every chest of the floor not opened yet takes that second's contents (tried in the game: the chests are placed again on leaving the menu, with the contents of the second you left it).
• Boss no. 12, Greygnarl, gives no new map: its first loot is a Yggdrasil leaf (100%), and it can drop the Dragonlord's map (5%).
• Fources against bosses: each blow of the party does ×1.1, then × the boss's resistance to the Fource's element; Gale Fource takes the better of two resistances (wind or lightning / blast), and so does Funereal Fource (darkness or earth). Table “Best Fource against each boss”.
• The quest 15 map (“Granite Tunnel of Woe Lv. 1”) is fixed: quality 2, seed 50, location no. 5 set by the quest (a map drawn at random with this seed could not be there). 21 other maps in the game have exactly the same name.
• Nose for Treasure counts the area's placed treasures (the game's treasure file): on a grotto floor, it answers “But nothing happens”. In another player's world, Nose for Treasure fails everywhere and Treasure Eye Land outside grottoes.
• Treasure Eye Land in a grotto: shows the staircase down on the top-screen map, even in an unexplored part, whether or not the boss has already been beaten (tried in the game). Elsewhere, it marks red chests.
• Completed grotto: once the boss is beaten, it no longer comes back, and chests already opened stay empty (the game keeps one flag per chest, 5 per floor). Everything comes back when you choose a map in the treasure map menu, even the same one: boss back, chests closed again.
• Saving: the church save does not keep the chosen map (on loading, no map is open: you have to choose one again, so the grotto starts afresh); the quicksave keeps the map, the beaten boss and the opened chests.

Single-monster floors

On arriving at a floor, the game stores what it needs to make monsters wander in a small memory of 11,344 bytes. When it gets too full, some of the floor's monsters can never appear.

Under the hood

What goes in, in order: 4,896 bytes always; the monsters' walking map, computed from the floor layout (16 bytes per walkable tile, 8 per passage between two neighbouring tiles, 4 per tile for its list of neighbours; the game drops passages if the first two exceed 4,128 bytes); 428 to 500 bytes for the monsters of the floor's table; then one 20-byte record per monster, from the lowest monster number to the highest.

• As soon as a record does not fit, the game stops there: the remaining monsters never appear on that floor (when the game picks one of them for a new wandering monster, nothing appears and it tries again on the next frame: the remaining ones appear at almost the usual pace).
• Large, very open floors (16 × 16, few walls) fill the memory: only the lowest-numbered monster is left. The 3 trapped chests (cannibox, mimic, Pandora's box: nos. 38 to 40) come before almost every monster.
• Hence the “metal-only” maps: the liquid metal slime (no. 27) even comes before the trapped chests, and the metal king slime, gem jamboree and gem slime are the lowest numbers in their tables. A few floors have no wandering monster at all (only the cannibox's record fits, or the memory is full before the records).
• Trapped chests: the ambush makes the chest's monster appear as a wandering monster. If its record did not fit, the chest opens without a fight, and its contents are lost until the grotto is reset. This happens on 1,615 floors in the game (missing record: Pandora's box on all of them, mimic on 1,266, cannibox on 597).
• The “My grotto in detail” tool strikes out, floor by floor, the monsters that never appear; the Grottoes page (Special maps tab) gives the list of “metal-only” maps and their chance for each base quality.

Single-monster floors: memory measured in the game on 21 floors, to the byte; the count of “metal-only” maps is identical to the community's.