diff --git a/README.md b/README.md
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@@ -1,3 +1,10 @@
 Simple SNES shoot-'em-up game.
 
 Run build.bat to build it. Assumes you have the wla assembler binaries and Neviksti's pcx2snes somewhere on your path.
+
+The main files are:
+pewpew.asm: main code file.
+memory.asm: definitions of variable names (and memory layout) used by the game.
+registers.asm: definitions & documentation of important SNES registers.
+header.asm: definition of ROM layout & SNES header information for wla.
+init.asm: boilerplate "initialize the hardware" macro.