diff --git a/Makefile.port b/Makefile.port
new file mode 100644
index 000000000..8361f2673
--- /dev/null
+++ b/Makefile.port
@@ -0,0 +1,254 @@
+# Options.
+
+# HOST_PLATFORM - Which platform we're building on.
+#
+# Determined automatically if not specified on command line.
+#
+# Supported values:
+# * i686-windows
+# * i686-linux
+
+HOST_PLATFORM ?=
+
+# TARGET_PLATFORM - Which platform to build for.
+#
+# Determined from HOST_PLATFORM if not specified on command line.
+#
+# Supported values:
+# * i686-windows
+# * i686-linux
+
+TARGET_PLATFORM ?=
+
+# ROMID - The ROM version to use.
+#
+# Can be set in your environment using
+#     $ export ROMID=...
+#
+# Supported values:
+#  * ntsc-final
+
+ROMID ?= ntsc-final
+
+# GCC_OPT_LVL - the optimisation level if building with gcc.
+#
+# Supported values: -O0, -O1, -O2, -O3, -Os, -Og
+
+GCC_OPT_LVL = -O0
+
+# ROM_SIZE - The desired ROM size in megabytes.
+#
+# All versions of the retail ROM are 32MB.
+#
+# If this is too low you might get this error from ld:
+# "final link failed: memory exhausted"
+
+ROM_SIZE := 32
+
+# DEBUG - Enable (1) or disable (0) the debug menu and crash screen.
+#
+# When enabled, press C-up and C-down simultaneously to toggle the debug menu.
+# Note that some emulators have problems displaying the crash screen text.
+
+DEBUG = 0
+
+################################################################################
+
+# Detect host platform if not specified.
+ifeq ($(HOST_PLATFORM),)
+	ifeq ($(OS),Windows_NT)
+		# assume msys for now
+		UNAME_OS := $(shell uname -s)
+		ifneq (,$(findstring MINGW64,$(UNAME_OS)))
+			HOST_PLATFORM := x86_64-windows
+		else
+			HOST_PLATFORM := i686-windows
+		endif
+	else # TODO
+		UNAME_ARCH := $(shell uname -p)
+		UNAME_OS := $(shell uname -s)
+		UNAME_OS := `echo $(UNAME_OS) | tr A-Z a-z`
+		HOST_PLATFORM := $(UNAME_ARCH)-$(UNAME_OS)
+	endif
+endif
+
+$(info Host platform: $(HOST_PLATFORM))
+
+# Set target platform to host platform if not specified.
+ifeq ($(TARGET_PLATFORM),)
+	TARGET_PLATFORM := $(HOST_PLATFORM)
+endif
+
+$(info Target platform: $(TARGET_PLATFORM))
+
+# Set whether the target arch is 64- or 32-bit.
+ifneq (,$(findstring 64,$(TARGET_PLATFORM)))
+	# TODO: we're not 64-bit compatible yet
+	$(error 64-bit target platforms are not supported yet.)
+	TARGET_64BIT = 1
+else # TODO
+	TARGET_64BIT = 0
+endif
+
+# Set whether the target is big-endian or little-endian.
+TARGET_BIG_ENDIAN = 0 # TODO
+
+# The VERSION constant is used in the source to handle version-specific code.
+ifeq ($(ROMID),ntsc-final)
+	VERSION = 2
+else
+	$(error ROM version $(VERSION) is not supported.)
+endif
+
+DEFINES := \
+	VERSION=$(VERSION) \
+	MATCHING=0 \
+	PAL=0 \
+	PIRACYCHECKS=0 \
+	ROM_SIZE=$(ROM_SIZE) \
+	_LANGUAGE_C=1
+
+ifeq ($(DEBUG),1)
+	DEFINES := $(DEFINES) DEBUG=1
+endif
+
+C_DEFINES := $(foreach d,$(DEFINES),-D$(d))
+
+A_DIR := src/assets/$(ROMID)
+B_DIR := build/$(ROMID)-port
+E_DIR := extracted/$(ROMID)
+
+ifneq (,$(findstring x86_64,$(TARGET_PLATFORM)))
+	TOOLCHAIN_ARCH := x86_64
+else # TODO
+	TOOLCHAIN_ARCH := i686
+endif
+
+ifneq (,$(findstring windows,$(TARGET_PLATFORM)))
+	TOOLCHAIN := $(TOOLCHAIN_ARCH)-w64-mingw32
+	TARGET_LDFLAGS := $(shell pkg-config sdl2 --libs) -lz -lopengl32
+	TARGET_CFLAGS := $(shell pkg-config sdl2 --cflags-only-I)
+else # TODO
+	TOOLCHAIN := $(TOOLCHAIN_ARCH)-linux-gnu
+	TARGET_LDFLAGS := $(shell pkg-config sdl2 --libs) -lGL -lz
+	TARGET_CFLAGS := $(shell pkg-config sdl2 --cflags-only-I)
+endif
+
+# These are still used in the port, but only to generate headers.
+LANG_JSON_FILES := $(shell find $(A_DIR) -path '*/lang/*.json')
+PADS_JSON_FILES := $(shell find $(A_DIR) -path '*/pads/*.json')
+TILES_JSON_FILES := $(shell find $(A_DIR) -path '*/tiles/*.json')
+
+C_FILES := $(shell find src/game port -name '*.c')
+C_FILES := $(C_FILES) \
+	$(wildcard src/lib/mp3/*.c) \
+	$(wildcard src/lib/naudio/*.c) \
+	$(wildcard src/lib/ultra/audio/*.c) \
+	$(wildcard src/lib/ultra/gu/*.c) \
+	src/lib/ultra/io/vimodentsclan1.c \
+	src/lib/ultra/io/vimodepallan1.c \
+	src/lib/ultra/io/vimodempallan1.c \
+	src/lib/ultra/io/vitbl.c \
+	$(wildcard src/lib/a*.c) \
+	src/lib/base.c \
+	src/lib/collision.c \
+	src/lib/debughud.c \
+	src/lib/dma.c \
+	src/lib/fault.c \
+	src/lib/joy.c \
+	$(wildcard src/lib/lib_*.c) \
+	src/lib/mema.c \
+	src/lib/memp.c \
+	src/lib/model.c \
+	src/lib/modelasm_c.c \
+	src/lib/mp3.c \
+	src/lib/mtx_c.c \
+	src/lib/mtx.c \
+	src/lib/music.c \
+	src/lib/path.c \
+	src/lib/profile.c \
+	src/lib/rdp.c \
+	src/lib/rmon.c \
+	src/lib/rng_c.c \
+	src/lib/rzip_c.c \
+	src/lib/snd.c \
+	src/lib/speaker.c \
+	src/lib/varsinit.c \
+	src/lib/vi.c \
+	src/textureconfig.c
+
+CXX_FILES :=$(shell find port -name '*.cpp')
+
+C_O_FILES := $(patsubst %.c, $(B_DIR)/%.o, $(C_FILES))
+CXX_O_FILES := $(patsubst %.cpp, $(B_DIR)/%.o, $(CXX_FILES))
+
+O_FILES := $(C_O_FILES) $(CXX_O_FILES)
+
+INCLUDES = \
+	-I include \
+	-I include/PR \
+	-I src/include \
+	-I src/generated/$(ROMID) \
+	-I src/lib/ultra/audio \
+	-I port/include
+
+CC := $(TOOLCHAIN)-gcc -std=gnu11
+CXX := $(TOOLCHAIN)-g++ -std=gnu++20
+ifneq (,$(CXX_O_FILES))
+	LD := $(CXX)
+else
+	LD := $(CC)
+endif
+
+$(C_O_FILES): OPT_LVL := $(GCC_OPT_LVL)
+
+COMMON_CFLAGS := $(C_DEFINES) -DAVOID_UB=1 $(INCLUDES) $(TARGET_CFLAGS) -g \
+	-fno-inline-functions \
+	-fno-strict-aliasing \
+	-funsigned-char \
+	-fwrapv \
+	-Wall \
+	-Wno-address \
+	-Wno-aggressive-loop-optimizations \
+	-Wno-int-in-bool-context \
+	-Wno-misleading-indentation \
+	-Wno-missing-braces \
+	-Wno-multichar \
+	-Wno-tautological-compare \
+	-Wno-unused-but-set-variable \
+	-Wno-unused-value \
+	-Wno-unused-variable
+
+CFLAGS := $(COMMON_CFLAGS) -Wno-pointer-sign
+CXXFLAGS := $(COMMON_CFLAGS) -Wno-unused-function
+LDFLAGS := $(TARGET_LDFLAGS)
+
+# Make ROMID available as an environment variable to all tooling.
+# (We use this a lot)
+export ROMID
+
+BIN := $(B_DIR)/pd.exe
+
+default: $(BIN)
+
+$(BIN): $(O_FILES)
+	$(LD) $(COMMON_CFLAGS) $(OPT_LVL) -o $(BIN) $^ $(LDFLAGS)
+
+$(B_DIR)/%.o: %.c
+	@mkdir -p $(dir $@)
+	$(CC) -c $(CFLAGS) $(OPT_LVL) -o $@ $<
+
+$(B_DIR)/%.o: %.cpp
+	@mkdir -p $(dir $@)
+	$(CXX) -c $(CXXFLAGS) $(OPT_LVL) -o $@ $<
+
+clean:
+	rm -rf build/$(ROMID)-port
+#	rm -rf src/generated/$(ROMID)
+
+allclean:
+	rm -rf build/*
+#	rm -rf src/generated
+
+codeclean:
+	find $(B_DIR)/game $(B_DIR)/inflate $(B_DIR)/lib -name '*.o' -delete