How the game loads a map

StarCraft reads a map up to three times, and each time it reads only the sections it needs then: a short read for the map list, a longer one when a game starts, and one more for the briefing. Before each read it checks VER, which must be 59, 63 or 205.

A read fails at the first section it needs that is missing, or at the first copy of a section that it does not accept. What is read before the failure stays read, but the map goes no further.

The map list read runs every time the list shows the map, again when a game is made with it, and again at the start. So the nine sections it needs are needed by every map, and a map that lacks one is shown in the list but cannot be chosen.

Melee and Use Map Settings#

The game type decides what the second read takes. Melee, and every type except Use Map Settings (Free for All, One on One, Capture the Flag, Greed, Slaughter, Sudden Death, Top vs Bottom and the team types), reads four sections: the strings, the terrain, the sprites and the units, plus the colours in a Brood War file. It never reads the map's triggers, locations, fog, unit settings, upgrades, technologies or availability.

Of the placed units, a melee game keeps only the start locations and the mineral fields, geysers and critters of Player 12. Of the unit sprites in THG2, it keeps only Player 12's. Every other unit is left out.

Use Map Settings reads everything else that matters to play.

What a map needs#

The smallest file each kind of game will load:

THG2 can be empty when the map has no sprites. Everything else is optional or for editors. MBRF, the briefing, is not needed: without it there is no briefing and nothing else changes. TYPE is looked for but never read.

When a map will not load#

What a player sees, and what causes it:

Which game#

Everything this page says about the game was checked in StarCraft: Brood War 1.16.1, the last version before Remastered. Remastered is known to differ in these ways:

• Its map list needs TRIG. A map with no TRIG section is Invalid Scenario in Remastered whatever the game type, where 1.16.1 lists it and plays it as melee.
• It reads VER 206, STRx and CRGB. 1.16.1 refuses VER 206 and never reads the other two.
• It passes over a STR copy shorter than 2 bytes, where 1.16.1 takes it.
• It reads text as UTF-8 when the bytes are valid UTF-8 (see STR).
• In a string, a colour carries on to the next line.

Twelve of the page's claims were also played in Remastered with probe maps, and in all but the TRIG one Remastered did what 1.16.1 does:

• a section one byte too long, and a UNIT section that ends in part of a record, refuse the map, with the same messages;
• a StarCraft 1.00 file with 255 locations, and a map with no MASK, start as melee and stop as Use Map Settings;
• a Brood War file with no COLR stops at the start of any game;
• a map with no MBRF plays, with no briefing;
• start locations come from the last UNIT section, so a melee game of a map that puts them in the first of two is lost at once;
• a Ghost placed cloaked starts cloaked only if its owner has Personal Cloaking;
• a hybrid file's UNIx is applied over its UNIS;
• a section the game never reads may run past the end of the file.

Where the page says a fact was found playing Remastered, it was. The rest has not been checked in Remastered; a map that 1.16.1 accepts, and that has a TRIG section, is the safe target.