Reverse Engineering the AI of Age of Empires 

there is a open ai machine learning, but for aoe2

It doesn't help that I'm just bad at games

You don't want to know alien tech - trust me.

@@luk3z861 what makes u think they are so advanced?

@@1AEGIS Well something created this world you know... We live in matrix.

Wololol

The ending to this video just cracks me up. Good work!

I think one of the Halo games was the first to use behaviour trees (but I may be misremembering)

I'm really enjoying just sitting down, solving problems and then taking people on that journey

Thanks! I've got some videos reverse engineering some other games you might find interesting

@@nathanbaggs The discovered the RCT one, amazing

I am fully prepared to admit that my research stopped at Wikipedia: "Age of Empires was mostly written in x86 32-bit assembly code totalling approximately 13,000 lines". Might be fun to dig into the graphics and have a look though

​@@nathanbaggs I remember reading an interview years ago where a dev stated that most of the rendering pipeline was written in assembly for performance reasons. So I imagine most of the rest of the game was written in C or C++ and they used inline assembly for specific parts.

Imagine writing today a game pure in assembly this people are goats

one could compare the number of lines for Rollercoaster Tycoon to do some sanity checks

Thanks for anecdote (: glad you’re enjoying that videos!

I am fully prepared to admit that my research stopped at Wikipedia: "Age of Empires was mostly written in x86 32-bit assembly code totalling approximately 13,000 lines". Might be fun to dig into the graphics and have a look though

Microsoft didn't develop AoE, it was developed by Ensemble Studios which was later bought by Microsoft.

It's nice when the RU-vid algorithm works

All makes sense, thanks for the insight

Glad you're enjoying it (:

Got to keep plugging away at these problems, can't let the computers win

I think that's an interesting idea for a video...

Honestly not sure what the nonsense was, probably some hand rolled optimisation. A code cave is just an unused section of a binary you can poke your own code

Mnemonics refers to the (often 3, but sometimes longer) letter assembly instruction names, like "mov", "adc", "xor", etc. "??" in the mnemonic area means that that ghidra isn't confident what that data is supposed to be, as it doesn't appear to be either intentional data or meaningful code. The "??" itself is not a defined mnemonic with any meaning, it's just an indicator that ghidra doesn't know what that data is. If you were to try to run the data there as code, it could do anything, because it's effectively completely random data. As you might imagine, treating random numbers as code is generally speaking not a good idea. Code caves are an informal name given to chunks of unused memory assigned to your process that don't contain actual code or data. They are usually a byproduct of something needing things to be aligned to some memory size. They're particularly useful for hacking or reverse engineering like this because nothing uses that data, so we're free to overwrite it with our own data. This lets us insert some instructions into the process that we might not otherwise be able to insert without breaking something else. If there was no free space in memory to insert your own code, you'd have to overwrite existing code, potentially completely breaking the game. Using code caves, you can insert your own code without overwriting things and make only a small edit somewhere to make execution jump into your code where appropriate.

My guess is it's some kind of lookup table the compiler inserted inline for the switch statement.

@@Artentuscompiler? Its hand written assembly

@@mattmurphy7030 according to what I could find on the internet, it was mostly the graphics code that was written in assembly, everything else is C++.

I live stream low level stuff most Sundays if you’re interested

Glad you found the channel and are enjoying it (and thanks for becoming a member!)

No worries

I’ve seen no evidence of the AI cheating, it looks like it has a bunch of initial build orders (based on some files). I suspect the difficulty is just how aggressive it is in attacking you and pursuing victory conditions (like wonders)

I am almost certain that the AI cheats on higher difficulties in the original releases of AOE I and II. This is widely believed to be the case in the community, although I don’t know if anyone has provided proof via source code or disassembly. For AOE II DE, the new AIs were lauded for being very skilled despite not cheating, which also implies that the original AI did cheat. Will be interesting to see if you can confirm this for AOE I via your analysis.

@@mitchlindgren I vividly remember spawning an "Impossible" difficulty AI in AoE2 editor like 20 years ago on a map where the AI did not have any means of producing anything, TC, nor vills, just military and other buildings or some similar condition where it's impossible to grow and I reached it after a few minutes and it randomly had all of those things.

I am fully prepared to admit that I did not do a lot of research on that part, I pretty much stopped at the Wikipedia article

I’ve got some more games in the pipeline

Interesting, thanks!

I’m still terrible at it though (:

There's still more to figure out in AoE, but I would like to look at 2 at some point

I'd rather spend the time making more videos (:

@@nathanbaggs w userpatch

Something I want to dig more into, some people have suggested that the assembly is just for the rendering code

What an interesting idea...

I think it would look similar but you'd lose all of the stuff assembly source contains like macros.

Depends if there's any transformative process (like macro expansion) along the way

@@nathanbaggs sure, Macros are lost, comments are lost. Formatting if you can really call that important is lost. Names of labels is probably lost? Since it converts to addresses and offsets. I don't know if assemblers have any optimizations in them like compilers do, but that might also affect it.

Glad you found and enjoyed this! (I have other videos on cheating...)

Thanks!

You must be watching this on 100x speed (:

@@nathanbaggs I reverse engineered your video.

Why?

@@ToTheGAMES to pay the devs?

More fun than actually playing the game

You’re right and I was surprised how well ghidra handled it. I guess the developers chose to stick to a well known ABI, which helps with RE

@@nathanbaggs the game wasn't 100% assembly, there was some C++, hence thiscall. Most of the assembly was for rendering.

I think maybe I'm just bad at the game

@@nathanbaggs maybe it helps if you know how the AI is thinking 😏