Mono Features

So what are the Cheat Engine mono features?

What is Mono?

Mono is a free and open-source project. Created to build an ECMA (European Computer Manufacturers Association) standard-compliant .NET Framework compatible set of tools. Including a C# compiler and a Common Language Runtime with just-in-time (JIT) compilation.

Side Note: The logo of Mono is a stylized monkey's face, mono being Spanish for monkey.

The Cheat Engine Mono feature are basically tools to help in Mono games. They can offer a different way to create and/or use cheats.

Let's setup infinite health in a Mono game. I'll be using Cuphead.

Attaching to the process

So if you attach to a Mono game then Cheat Engine initializes the Mono features and there will be a new Mono menu item in the Cheat Engine main form. But you'll notice if you use openProcess in some Lua script, the Mono menu item doesn't show up. With Mono we want to us mono_OpenProcess to open the process or use mono_initialize to initialize the Mono features. The main thing to note is it takes a process ID (number), not a process name (string). Then we just need to use LaunchMonoDataCollector to activate the Mono features, it needs to be called after attaching to the process (after the Mono features are initialized).

--[============================================================[
	Process			: Cuphead.exe
	Game Version	: 5.6.2.10718
	CE Version		: 6.7
]============================================================]--
PROCESS_NAME = 'Cuphead.exe'
GAME_TITLE = 'Cuphead'
-- GAME_VERSION = '5.6.2.10718'
local autoAttachTimerInterval = 100
local autoAttachTimerTicks = 0
local autoAttachTimerTickMax = 5000
local autoAttachTimer = nil
local function autoAttachTimer_tick(timer)
	if autoAttachTimerTickMax > 0 and autoAttachTimerTicks >= autoAttachTimerTickMax then
		timer.destroy()
	end
	if getProcessIDFromProcessName(PROCESS_NAME) ~= nil then
		timer.destroy()
		--openProcess(PROCESS_NAME)
		mono_OpenProcess(getProcessIDFromProcessName(PROCESS_NAME))
		local InjectedMono = LaunchMonoDataCollector()
		if InjectedMono and InjectedMono ~= 0 then
			print(string.format('Mono Features Enabled: %X', InjectedMono))
		end
	end
	autoAttachTimerTicks = autoAttachTimerTicks + 1
end
autoAttachTimer = createTimer(MainForm)
autoAttachTimer.Interval = autoAttachTimerInterval
autoAttachTimer.OnTimer = autoAttachTimer_tick

Working with Mono in scripts

So let's say we already found health with traditional value scanning. If you have the Mono features enabled and setup an injection script then you will see an addresses like this "PlayerStatsManager:TakeDamage+ABC" instead of just a game plus offset address.

So if we setup a script we can use the Mono address to make if more robust to deal with game updates better.

{$STRICT}
define(bytes,89 47 60)
////
//// ------------------------------ ENABLE ------------------------------
[ENABLE]
assert(PlayerStatsManager:TakeDamage+8A, bytes)
PlayerStatsManager:TakeDamage+8A:
  nop
  nop
  nop
////
//// ------------------------------ DISABLE ------------------------------
[DISABLE]
PlayerStatsManager:TakeDamage+8A:
  db bytes
  // mov [edi+60],eax

But if we try to enable this script before the player takes damage, then you will find it won't enable. So let's fix that.

So fist we need to understand why scripts using Mono addresses don't enable before some given action. Well in short, Mono uses a JIT compiler.

Just-in-time (JIT) compilation (a.k.a.: dynamic translation or run-time compilation), involves compilation during execution of a program (at run time) rather than prior to execution.

So to get the game to JIT (compile) the code we need to preform some action, for the above code we have to take damage. So how do we JIT the code, we can use mono_findMethod with mono_compile_method.

Finding the Namespace

To do that we need the Namespace, Class, and Method names, we have the Class and Method in the above code. We can use the find tool of the Mono Dissect Form to find the Namespace by searching for the class name.

JIT the method

Then we can setup a script like this

{$STRICT}
define(bytes,89 47 60)
////
//// ------------------------------ ENABLE ------------------------------
[ENABLE]
{$lua}
if syntaxcheck then return end
local mId = mono_findMethod('Assembly-CSharp', 'PlayerStatsManager', 'TakeDamage')
mono_compile_method(mId)
{$asm}

assert(PlayerStatsManager:TakeDamage+8A, bytes)
PlayerStatsManager:TakeDamage+8A:
  nop
  nop
  nop


////
//// ------------------------------ DISABLE ------------------------------
[DISABLE]
PlayerStatsManager:TakeDamage+8A:
  db bytes
  // mov [edi+60],eax

Now with this we can just enable the script after the Mono features have been enabled.

Make method only return

We could also try to just make the method return with out doing any thing.

{$STRICT}
define(bytes,55)
////
//// ------------------------------ ENABLE ------------------------------
[ENABLE]
{$lua}
if syntaxcheck then return end
local mId = mono_findMethod('Assembly-CSharp', 'PlayerStatsManager', 'TakeDamage')
mono_compile_method(mId)
{$asm}

assert(PlayerStatsManager:TakeDamage, bytes)
PlayerStatsManager:TakeDamage:
  ret


////
//// ------------------------------ DISABLE ------------------------------
[DISABLE]
PlayerStatsManager:TakeDamage:
  db bytes
  // push ebp

See also

• Mono
• Mono Dissect Form
• Mono Structure Dissection
• Mono Lua
  • Mono Lua Functions
• Mono AA Commands
• Tutorial - Mono - Basic