diff --git a/Dockerfile b/Dockerfile
index ff2f85d4..6aa360d5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -27,6 +27,8 @@ COPY hooklib hooklib
 COPY iccard iccard
 COPY idzhook idzhook
 COPY idzio idzio
+COPY mercuryhook mercuryhook
+COPY mercuryio mercuryio
 COPY jvs jvs
 COPY minihook minihook
 COPY mu3hook mu3hook
diff --git a/Package.mk b/Package.mk
index c18c0334..fcac6f9f 100644
--- a/Package.mk
+++ b/Package.mk
@@ -28,6 +28,21 @@ $(BUILD_DIR_ZIP)/idz.zip:
 	$(V)strip $(BUILD_DIR_ZIP)/idz/*.{exe,dll}
 	$(V)cd $(BUILD_DIR_ZIP)/idz ; zip -r ../idz.zip *
 
+$(BUILD_DIR_ZIP)/mercury.zip:
+	$(V)echo ... $@
+	$(V)mkdir -p $(BUILD_DIR_ZIP)/mercury
+	$(V)mkdir -p $(BUILD_DIR_ZIP)/mercury/DEVICE
+	$(V)cp $(BUILD_DIR_64)/subprojects/capnhook/inject/inject.exe \
+		$(BUILD_DIR_64)/mercuryhook/mercuryhook.dll \
+		$(DIST_DIR)/mercury/segatools.ini \
+		$(DIST_DIR)/mercury/start.bat \
+    	$(BUILD_DIR_ZIP)/mercury
+	$(V)cp pki/billing.pub \
+		pki/ca.crt \
+    	$(BUILD_DIR_ZIP)/mercury/DEVICE
+	$(V)strip $(BUILD_DIR_ZIP)/mercury/*.{exe,dll}
+	$(V)cd $(BUILD_DIR_ZIP)/mercury ; zip -r ../mercury.zip *
+
 $(BUILD_DIR_ZIP)/doc.zip: \
 		$(DOC_DIR)/config \
 		$(DOC_DIR)/chunihook.md \
@@ -40,6 +55,7 @@ $(BUILD_DIR_ZIP)/segatools.zip: \
 		$(BUILD_DIR_ZIP)/chuni.zip \
 		$(BUILD_DIR_ZIP)/doc.zip \
 		$(BUILD_DIR_ZIP)/idz.zip \
+		$(BUILD_DIR_ZIP)/mercury.zip \
 		CHANGELOG.md \
 		README.md \
 
diff --git a/board/io4.c b/board/io4.c
index efad62ff..e7fe9e37 100644
--- a/board/io4.c
+++ b/board/io4.c
@@ -28,6 +28,7 @@ enum {
     IO4_CMD_CLEAR_BOARD_STATUS = 0x03,
     IO4_CMD_SET_GENERAL_OUTPUT = 0x04,
     IO4_CMD_SET_PWM_OUTPUT     = 0x05,
+    IO4_CMD_UNIMPLEMENTED      = 0x41,
     IO4_CMD_UPDATE_FIRMWARE    = 0x85,
 };
 
@@ -234,7 +235,12 @@ static HRESULT io4_handle_write(struct irp *irp)
     case IO4_CMD_UPDATE_FIRMWARE:
         dprintf("USB I/O: Update firmware..?\n");
 
-        return E_FAIL;
+        return E_FAIL;    
+        
+    case IO4_CMD_UNIMPLEMENTED:
+        //dprintf("USB I/O: Unimplemented cmd 41\n");
+
+        return S_OK;
 
     default:
         dprintf("USB I/O: Unknown command %02x\n", out.cmd);
diff --git a/dist/mercury/segatools.ini b/dist/mercury/segatools.ini
new file mode 100644
index 00000000..c439f13c
--- /dev/null
+++ b/dist/mercury/segatools.ini
@@ -0,0 +1,42 @@
+[vfs]
+; Insert the path to the game AMFS directory here (contains ICF1 and ICF2)
+amfs=amfs
+; Create an empty directory somewhere and insert the path here.
+; This directory may be shared between multiple SEGA games.
+; NOTE: This has nothing to do with Windows %APPDATA%.
+appdata=appdata
+option=option
+
+[dns]
+; Insert the hostname or IP address of the server you wish to use here.
+; Note that 127.0.0.1, localhost etc are specifically rejected.
+default=127.0.0.1
+
+[ds]
+; Region code on the emulated AMEX board DS EEPROM.
+; 1: Japan
+; 4: Export (some UI elements in English)
+;
+; NOTE: Changing this setting causes a factory reset.
+region=1
+
+[netenv]
+; Simulate an ideal LAN environment. This may interfere with head-to-head play.
+; SEGA games are somewhat picky about their LAN environment, so leaving this
+; setting enabled is recommended.
+enable=1
+
+[keychip]
+; The /24 LAN subnet that the emulated keychip will tell the game to expect.
+; If you disable netenv then you must set this to your LAN's IP subnet, and
+; that subnet must start with 192.168.
+subnet=192.168.250.0
+
+
+[io4]
+; Input API selection for JVS input emulator.
+test=0x31
+service=0x32
+
+[gfx]
+enable=0
diff --git a/dist/mercury/start.bat b/dist/mercury/start.bat
new file mode 100644
index 00000000..437722ee
--- /dev/null
+++ b/dist/mercury/start.bat
@@ -0,0 +1,10 @@
+@echo off
+pushd %~dp0
+taskkill /f /im amdaemon.exe > nul 2>&1
+:LOOP
+inject -d -k mercuryhook.dll amdaemon.exe -c config.json config_region_jpn.json config_video_clone.json config_video_clone_flip.json config_video_dual.json config_video_dual_flip.json
+inject -d -k mercuryhook.dll ../WindowsNoEditor/Mercury.exe
+taskkill /f /im amdaemon.exe > nul 2>&1
+echo.
+echo Game processes have terminated
+pause
\ No newline at end of file
diff --git a/mercuryhook/config.c b/mercuryhook/config.c
new file mode 100644
index 00000000..9a61aad8
--- /dev/null
+++ b/mercuryhook/config.c
@@ -0,0 +1,43 @@
+#include <assert.h>
+#include <stddef.h>
+
+#include "board/config.h"
+
+#include "hooklib/config.h"
+#include "hooklib/dvd.h"
+#include "hooklib/gfx.h"
+
+#include "mercuryhook/config.h"
+
+#include "platform/config.h"
+
+void mercury_dll_config_load(
+        struct mercury_dll_config *cfg,
+        const wchar_t *filename)
+{
+    assert(cfg != NULL);
+    assert(filename != NULL);
+
+    GetPrivateProfileStringW(
+            L"mercuryio",
+            L"path",
+            L"",
+            cfg->path,
+            _countof(cfg->path),
+            filename);
+}
+
+void mercury_hook_config_load(
+        struct mercury_hook_config *cfg,
+        const wchar_t *filename)
+{
+    assert(cfg != NULL);
+    assert(filename != NULL);
+
+    platform_config_load(&cfg->platform, filename);
+    aime_config_load(&cfg->aime, filename);
+    dvd_config_load(&cfg->dvd, filename);
+    io4_config_load(&cfg->io4, filename);
+    gfx_config_load(&cfg->gfx, filename);
+    mercury_dll_config_load(&cfg->dll, filename);
+}
diff --git a/mercuryhook/config.h b/mercuryhook/config.h
new file mode 100644
index 00000000..627e69c4
--- /dev/null
+++ b/mercuryhook/config.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <stddef.h>
+
+#include "board/config.h"
+
+#include "hooklib/dvd.h"
+#include "hooklib/gfx.h"
+
+#include "mercuryhook/mercury-dll.h"
+
+#include "platform/config.h"
+
+struct mercury_hook_config {
+    struct platform_config platform;
+    struct aime_config aime;
+    struct dvd_config dvd;
+    struct io4_config io4;
+    struct gfx_config gfx;
+    struct mercury_dll_config dll;
+};
+
+void mercury_dll_config_load(
+        struct mercury_dll_config *cfg,
+        const wchar_t *filename);
+
+void mercury_hook_config_load(
+        struct mercury_hook_config *cfg,
+        const wchar_t *filename);
diff --git a/mercuryhook/dllmain.c b/mercuryhook/dllmain.c
new file mode 100644
index 00000000..a362f7b8
--- /dev/null
+++ b/mercuryhook/dllmain.c
@@ -0,0 +1,109 @@
+#include <windows.h>
+
+#include "board/io4.h"
+#include "board/sg-reader.h"
+#include "board/vfd.h"
+
+#include "hook/process.h"
+
+#include "hooklib/serial.h"
+#include "hooklib/spike.h"
+
+#include "mercuryhook/config.h"
+#include "mercuryhook/io4.h"
+#include "mercuryhook/mercury-dll.h"
+
+#include "platform/platform.h"
+
+#include "util/dprintf.h"
+
+static HMODULE mercury_hook_mod;
+static process_entry_t mercury_startup;
+static struct mercury_hook_config mercury_hook_cfg;
+
+/* This hook is based on mu3hook, with leaked mercuryhook i/o codes. */
+
+static DWORD CALLBACK mercury_pre_startup(void)
+{
+    HRESULT hr;
+
+    dprintf("--- Begin mercury_pre_startup ---\n");
+
+    /* Load config */
+
+    mercury_hook_config_load(&mercury_hook_cfg, L".\\segatools.ini");
+
+    /* Hook Win32 APIs */
+
+    dvd_hook_init(&mercury_hook_cfg.dvd, mercury_hook_mod);
+    gfx_hook_init(&mercury_hook_cfg.gfx, mercury_hook_mod);
+    serial_hook_init();
+
+    /* Initialize emulation hooks */
+
+    hr = platform_hook_init(
+            &mercury_hook_cfg.platform,
+            "SDFE",
+            "ACA1",
+            mercury_hook_mod);
+
+    if (FAILED(hr)) {
+        goto fail;
+    }
+
+    hr = sg_reader_hook_init(&mercury_hook_cfg.aime, 1, mercury_hook_mod);
+
+    if (FAILED(hr)) {
+        goto fail;
+    }
+
+    hr = vfd_hook_init(2);
+
+    if (FAILED(hr)) {
+        goto fail;
+    }
+
+    hr = mercury_dll_init(&mercury_hook_cfg.dll, mercury_hook_mod);
+
+    if (FAILED(hr)) {
+        goto fail;
+    }
+
+    hr = mercury_io4_hook_init(&mercury_hook_cfg.io4);
+
+    if (FAILED(hr)) {
+        goto fail;
+    }
+
+    /* Initialize debug helpers */
+
+    spike_hook_init(L".\\segatools.ini");
+
+    dprintf("---  End  mercury_pre_startup ---\n");
+
+    /* Jump to EXE start address */
+
+    return mercury_startup();
+
+fail:
+    ExitProcess(EXIT_FAILURE);
+}
+
+BOOL WINAPI DllMain(HMODULE mod, DWORD cause, void *ctx)
+{
+    HRESULT hr;
+
+    if (cause != DLL_PROCESS_ATTACH) {
+        return TRUE;
+    }
+
+    mercury_hook_mod = mod;
+
+    hr = process_hijack_startup(mercury_pre_startup, &mercury_startup);
+
+    if (!SUCCEEDED(hr)) {
+        dprintf("Failed to hijack process startup: %x\n", (int) hr);
+    }
+
+    return SUCCEEDED(hr);
+}
diff --git a/mercuryhook/io4.c b/mercuryhook/io4.c
new file mode 100644
index 00000000..2ff0e831
--- /dev/null
+++ b/mercuryhook/io4.c
@@ -0,0 +1,64 @@
+#include <windows.h>
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "board/io4.h"
+
+#include "mercuryhook/mercury-dll.h"
+
+#include "util/dprintf.h"
+
+static HRESULT mercury_io4_poll(void *ctx, struct io4_state *state);
+
+static const struct io4_ops mercury_io4_ops = {
+    .poll = mercury_io4_poll,
+};
+
+HRESULT mercury_io4_hook_init(const struct io4_config *cfg)
+{
+    HRESULT hr;
+
+    assert(mercury_dll.init != NULL);
+
+    hr = io4_hook_init(cfg, &mercury_io4_ops, NULL);
+
+    if (FAILED(hr)) {
+        return hr;
+    }
+
+    return mercury_dll.init();
+}
+
+static HRESULT mercury_io4_poll(void *ctx, struct io4_state *state)
+{
+    uint8_t opbtn;
+    HRESULT hr;
+
+    assert(mercury_dll.poll != NULL);
+    assert(mercury_dll.get_opbtns != NULL);
+    assert(mercury_dll.get_gamebtns != NULL);
+
+    memset(state, 0, sizeof(*state));
+
+    hr = mercury_dll.poll();
+
+    if (FAILED(hr)) {
+        return hr;
+    }
+
+    opbtn = 0;
+
+    mercury_dll.get_opbtns(&opbtn);
+
+    if (opbtn & MAI2_IO_OPBTN_TEST) {
+        state->buttons[0] |= IO4_BUTTON_TEST;
+    }
+
+    if (opbtn & MAI2_IO_OPBTN_SERVICE) {
+        state->buttons[0] |= IO4_BUTTON_SERVICE;
+    }
+
+    return S_OK;
+}
diff --git a/mercuryhook/io4.h b/mercuryhook/io4.h
new file mode 100644
index 00000000..87dc6d78
--- /dev/null
+++ b/mercuryhook/io4.h
@@ -0,0 +1,7 @@
+#pragma once
+
+#include <windows.h>
+
+#include "board/io4.h"
+
+HRESULT mercury_io4_hook_init(const struct io4_config *cfg);
diff --git a/mercuryhook/mercury-dll.c b/mercuryhook/mercury-dll.c
new file mode 100644
index 00000000..6873820c
--- /dev/null
+++ b/mercuryhook/mercury-dll.c
@@ -0,0 +1,109 @@
+#include <windows.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "mercuryhook/mercury-dll.h"
+
+#include "util/dll-bind.h"
+#include "util/dprintf.h"
+
+const struct dll_bind_sym mercury_dll_syms[] = {
+    {
+        .sym = "mercury_io_init",
+        .off = offsetof(struct mercury_dll, init),
+    }, {
+        .sym = "mercury_io_poll",
+        .off = offsetof(struct mercury_dll, poll),
+    }, {
+        .sym = "mercury_io_get_opbtns",
+        .off = offsetof(struct mercury_dll, get_opbtns),
+    }, {
+        .sym = "mercury_io_get_gamebtns",
+        .off = offsetof(struct mercury_dll, get_gamebtns),
+    }
+};
+
+struct mercury_dll mercury_dll;
+
+// Copypasta DLL binding and diagnostic message boilerplate.
+// Not much of this lends itself to being easily factored out. Also there
+// will be a lot of API-specific branching code here eventually as new API
+// versions get defined, so even though these functions all look the same
+// now this won't remain the case forever.
+
+HRESULT mercury_dll_init(const struct mercury_dll_config *cfg, HINSTANCE self)
+{
+    uint16_t (*get_api_version)(void);
+    const struct dll_bind_sym *sym;
+    HINSTANCE owned;
+    HINSTANCE src;
+    HRESULT hr;
+
+    assert(cfg != NULL);
+    assert(self != NULL);
+
+    if (cfg->path[0] != L'\0') {
+        owned = LoadLibraryW(cfg->path);
+
+        if (owned == NULL) {
+            hr = HRESULT_FROM_WIN32(GetLastError());
+            dprintf("Wacca IO: Failed to load IO DLL: %lx: %S\n",
+                    hr,
+                    cfg->path);
+
+            goto end;
+        }
+
+        dprintf("Wacca IO: Using custom IO DLL: %S\n", cfg->path);
+        src = owned;
+    } else {
+        owned = NULL;
+        src = self;
+    }
+
+    get_api_version = (void *) GetProcAddress(src, "mercury_io_get_api_version");
+
+    if (get_api_version != NULL) {
+        mercury_dll.api_version = get_api_version();
+    } else {
+        mercury_dll.api_version = 0x0100;
+        dprintf("Custom IO DLL does not expose mercury_io_get_api_version, "
+                "assuming API version 1.0.\n"
+                "Please ask the developer to update their DLL.\n");
+    }
+
+    if (mercury_dll.api_version >= 0x0200) {
+        hr = E_NOTIMPL;
+        dprintf("Wacca IO: Custom IO DLL implements an unsupported "
+                "API version (%#04x). Please update Segatools.\n",
+                mercury_dll.api_version);
+
+        goto end;
+    }
+
+    sym = mercury_dll_syms;
+    hr = dll_bind(&mercury_dll, src, &sym, _countof(mercury_dll_syms));
+
+    if (FAILED(hr)) {
+        if (src != self) {
+            dprintf("Wacca IO: Custom IO DLL does not provide function "
+                    "\"%s\". Please contact your IO DLL's developer for "
+                    "further assistance.\n",
+                    sym->sym);
+
+            goto end;
+        } else {
+            dprintf("Internal error: could not reflect \"%s\"\n", sym->sym);
+        }
+    }
+
+    owned = NULL;
+
+end:
+    if (owned != NULL) {
+        FreeLibrary(owned);
+    }
+
+    return hr;
+}
diff --git a/mercuryhook/mercury-dll.h b/mercuryhook/mercury-dll.h
new file mode 100644
index 00000000..4e679a84
--- /dev/null
+++ b/mercuryhook/mercury-dll.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <windows.h>
+
+#include "mercuryio/mercuryio.h"
+
+struct mercury_dll {
+    uint16_t api_version;
+    HRESULT (*init)(void);
+    HRESULT (*poll)(void);
+    void (*get_opbtns)(uint8_t *opbtn);
+    void (*get_gamebtns)(uint16_t *player1, uint16_t *player2);
+};
+
+struct mercury_dll_config {
+    wchar_t path[MAX_PATH];
+};
+
+extern struct mercury_dll mercury_dll;
+
+HRESULT mercury_dll_init(const struct mercury_dll_config *cfg, HINSTANCE self);
diff --git a/mercuryhook/mercuryhook.def b/mercuryhook/mercuryhook.def
new file mode 100644
index 00000000..916d2785
--- /dev/null
+++ b/mercuryhook/mercuryhook.def
@@ -0,0 +1,19 @@
+LIBRARY mercuryhook
+
+EXPORTS
+    Direct3DCreate9
+    aime_io_get_api_version
+    aime_io_init
+    aime_io_led_set_color
+    aime_io_nfc_get_aime_id
+    aime_io_nfc_get_felica_id
+    aime_io_nfc_poll
+    amDllVideoClose @2
+    amDllVideoGetVBiosVersion @4
+    amDllVideoOpen @1
+    amDllVideoSetResolution @3
+    mercury_io_get_api_version
+    mercury_io_get_gamebtns
+    mercury_io_get_opbtns
+    mercury_io_init
+    mercury_io_poll
\ No newline at end of file
diff --git a/mercuryhook/meson.build b/mercuryhook/meson.build
new file mode 100644
index 00000000..5fc141c1
--- /dev/null
+++ b/mercuryhook/meson.build
@@ -0,0 +1,29 @@
+shared_library(
+    'mercuryhook',
+    name_prefix : '',
+    include_directories : inc,
+    implicit_include_directories : false,
+    vs_module_defs : 'mercuryhook.def',
+    c_pch : '../precompiled.h',
+    dependencies : [
+        capnhook.get_variable('hook_dep'),
+        capnhook.get_variable('hooklib_dep'),
+    ],
+    link_with : [
+        aimeio_lib,
+        board_lib,
+        hooklib_lib,
+        mercuryio_lib,
+        platform_lib,
+        util_lib,
+    ],
+    sources : [
+        'config.c',
+        'config.h',
+        'dllmain.c',
+        'io4.c',
+        'io4.h',
+        'mercury-dll.c',
+        'mercury-dll.h'
+    ],
+)
diff --git a/mercuryio/config.c b/mercuryio/config.c
new file mode 100644
index 00000000..3b627899
--- /dev/null
+++ b/mercuryio/config.c
@@ -0,0 +1,25 @@
+#include <windows.h>
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#include "mercuryio/config.h"
+
+/*
+Wacca Default key binding
+*/
+
+void mercury_io_config_load(
+        struct mercury_io_config *cfg,
+        const wchar_t *filename)
+{
+    wchar_t key[16];
+    int i;
+
+    assert(cfg != NULL);
+    assert(filename != NULL);
+
+    cfg->vk_test = GetPrivateProfileIntW(L"io4", L"test", '1', filename);
+    cfg->vk_service = GetPrivateProfileIntW(L"io4", L"service", '2', filename);
+}
diff --git a/mercuryio/config.h b/mercuryio/config.h
new file mode 100644
index 00000000..69cdf326
--- /dev/null
+++ b/mercuryio/config.h
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <stdbool.h>
+
+struct mercury_io_config {
+    uint8_t vk_test;
+    uint8_t vk_service;
+    uint8_t vk_1p_btn[9];
+    uint8_t vk_2p_btn[9];
+};
+
+void mercury_io_config_load(
+        struct mercury_io_config *cfg,
+        const wchar_t *filename);
diff --git a/mercuryio/mercuryio.c b/mercuryio/mercuryio.c
new file mode 100644
index 00000000..93266ab3
--- /dev/null
+++ b/mercuryio/mercuryio.c
@@ -0,0 +1,133 @@
+#include <windows.h>
+
+#include <limits.h>
+#include <stdint.h>
+
+#include "mercuryio/mercuryio.h"
+#include "mercuryio/config.h"
+
+static uint8_t mercury_opbtn;
+static uint16_t mercury_player1_btn;
+static uint16_t mercury_player2_btn;
+static struct mercury_io_config mercury_io_cfg;
+
+uint16_t mercury_io_get_api_version(void)
+{
+    return 0x0100;
+}
+
+HRESULT mercury_io_init(void)
+{
+    mercury_io_config_load(&mercury_io_cfg, L".\\segatools.ini");
+
+    return S_OK;
+}
+
+HRESULT mercury_io_poll(void)
+{
+    mercury_opbtn = 0;
+    mercury_player1_btn = 0;
+    mercury_player2_btn = 0;
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_test)) {
+        mercury_opbtn |= MAI2_IO_OPBTN_TEST;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_service)) {
+        mercury_opbtn |= MAI2_IO_OPBTN_SERVICE;
+    }
+
+    //Player 1
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[0])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_1;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[1])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_2;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[2])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_3;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[3])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_4;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[4])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_5;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[5])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_6;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[6])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_7;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[7])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_8;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_1p_btn[8])) {
+        mercury_player1_btn |= MAI2_IO_GAMEBTN_SELECT;
+    }
+
+    //Player 2
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[0])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_1;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[1])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_2;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[2])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_3;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[3])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_4;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[4])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_5;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[5])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_6;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[6])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_7;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[7])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_8;
+    }
+
+    if (GetAsyncKeyState(mercury_io_cfg.vk_2p_btn[8])) {
+        mercury_player2_btn |= MAI2_IO_GAMEBTN_SELECT;
+    }
+
+    return S_OK;
+}
+
+void mercury_io_get_opbtns(uint8_t *opbtn)
+{
+    if (opbtn != NULL) {
+        *opbtn = mercury_opbtn;
+    }
+}
+
+void mercury_io_get_gamebtns(uint16_t *player1, uint16_t *player2)
+{
+    if (player1 != NULL) {
+        *player1 = mercury_player1_btn;
+    }
+
+    if (player2 != NULL ){
+        *player2 = mercury_player2_btn;
+    }
+}
\ No newline at end of file
diff --git a/mercuryio/mercuryio.h b/mercuryio/mercuryio.h
new file mode 100644
index 00000000..85b3d5ab
--- /dev/null
+++ b/mercuryio/mercuryio.h
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <windows.h>
+
+#include <stdint.h>
+
+enum {
+    MAI2_IO_OPBTN_TEST = 0x01,
+    MAI2_IO_OPBTN_SERVICE = 0x02,
+};
+
+enum {
+    MAI2_IO_GAMEBTN_1 = 0x01,
+    MAI2_IO_GAMEBTN_2 = 0x02,
+    MAI2_IO_GAMEBTN_3 = 0x04,
+    MAI2_IO_GAMEBTN_4 = 0x08,
+    MAI2_IO_GAMEBTN_5 = 0x10,
+    MAI2_IO_GAMEBTN_6 = 0x20,
+    MAI2_IO_GAMEBTN_7 = 0x40,
+    MAI2_IO_GAMEBTN_8 = 0x80,
+    MAI2_IO_GAMEBTN_SELECT = 0x100,
+};
+
+/* Get the version of the Wacca IO API that this DLL supports. This
+   function should return a positive 16-bit integer, where the high byte is
+   the major version and the low byte is the minor version (as defined by the
+   Semantic Versioning standard).
+
+   The latest API version as of this writing is 0x0100. */
+
+uint16_t mercury_io_get_api_version(void);
+
+/* Initialize the IO DLL. This is the second function that will be called on
+   your DLL, after mercury_io_get_api_version.
+
+   All subsequent calls to this API may originate from arbitrary threads.
+
+   Minimum API version: 0x0100 */
+
+HRESULT mercury_io_init(void);
+
+/* Send any queued outputs (of which there are currently none, though this may
+   change in subsequent API versions) and retrieve any new inputs.
+
+   Minimum API version: 0x0100 */
+
+HRESULT mercury_io_poll(void);
+
+/* Get the state of the cabinet's operator buttons as of the last poll. See
+   MAI2_IO_OPBTN enum above: this contains bit mask definitions for button
+   states returned in *opbtn. All buttons are active-high.
+
+   Minimum API version: 0x0100 */
+
+void mercury_io_get_opbtns(uint8_t *opbtn);
+
+/* Get the state of the cabinet's gameplay buttons as of the last poll. See
+   MAI2_IO_GAMEBTN enum above for bit mask definitions. Inputs are split into
+   a left hand side set of inputs and a right hand side set of inputs: the bit
+   mappings are the same in both cases.
+
+   All buttons are active-high, even though some buttons' electrical signals
+   on a real cabinet are active-low.
+
+   Minimum API version: 0x0100 */
+
+void mercury_io_get_gamebtns(uint16_t *player1, uint16_t *player2);
diff --git a/mercuryio/meson.build b/mercuryio/meson.build
new file mode 100644
index 00000000..813958a0
--- /dev/null
+++ b/mercuryio/meson.build
@@ -0,0 +1,13 @@
+mercuryio_lib = static_library(
+    'mercuryio',
+    name_prefix : '',
+    include_directories : inc,
+    implicit_include_directories : false,
+    c_pch : '../precompiled.h',
+    sources : [
+        'mercuryio.c',
+        'mercuryio.h',
+        'config.c',
+        'config.h',
+    ],
+)
diff --git a/meson.build b/meson.build
index 50660ad1..f143e72b 100644
--- a/meson.build
+++ b/meson.build
@@ -48,9 +48,11 @@ subdir('chuniio')
 subdir('divaio')
 subdir('idzio')
 subdir('mu3io')
+subdir('mercuryio')
 
 subdir('chunihook')
 subdir('divahook')
 subdir('idzhook')
 subdir('minihook')
 subdir('mu3hook')
+subdir('mercuryhook')