Making a Clone of Civ II

[axx]

That's lots of boing.pngs I've been messing around with SDL yesterday, I'll try to set something up for civ2 now. Your library should be helpful by the looks of things. Well the SDL UI and the core game could be 2 projects, I think CivONE does that, it's also using an SDL C# wrapper. As for the roadmap there is none, I'm just dealing with stuff on the go, but it's pretty obvious the game should include ToT and support Lua. You could use the same SAV format but make something like SAVx which makes more than 7/8 loops for reading tribe data (in that case there should be another byte in the beginning of file which tells you how many civs there are). Then make every byte into short or int so more than 256-whatever can be saved. Or just go to a more modern format like you said.

 

[Blake00]

Anyways made a video on what I've done sofar, don't mind the tile gaps on edges, I need to fill them up but lazy. I've addressed some memory leaks so GC isn't doing much work (seen at end of video).

Wow that video is amazing mate. You totally recapture the feel of the original! I also love how there's a stealth bomber in ancient Rome in your test save haha!

Oh and regarding earlier posts about figuring out differences between MGE & ToT sav and scenario formats there are some old conversion programs out there but I don't know if their source was released, as that seeing what happens in the conversion process would probably be useful! No doubt others here know way more about all that stuff though, but thought I'd mention it.

.

 

[axx]

Oddly I just joined this forum as I was heading in this direction. I've started disassembling and looking at how various things work in ghidra/x64dbg. The isometric grid issue was a right pain in the backside for me too as it doesn't use the normal algorithm for generating an isometric map! grr..

Have you tried using retdec? It attempts to make a .c code from the exe. I tried it on simple .exe I wrote using C and I'm impressed at what it manages to make.
Also tried it on civ2.exe but I get a memory error I'm attempting to solve.

 

[joe@joesblog]

Have you tried using retdec? It attempts to make a .c code from the exe. I tried it on simple .exe I wrote using C and I'm impressed at what it manages to make.
Also tried it on civ2.exe but I get a memory error I'm attempting to solve.

Are you looking at the MGE executable?

I went through quite a few including IDA and I think retdec though they pretty much do a similar jobs and both have their advantages in the stuff they output (ghidra seems to output the best pseudo c code though imho). However when I tried retdec I think it stumbles on the analysis of big files. What's the memory error you're getting? Is it getting stuck on the flow analysis?

Also something cool; the civ2 asm has its own debug methods, they're useful in figuring out bits and pieces. (There are string references to cpp files, a way to find what functions are responsible)

 

[axx]

Are you looking at the MGE executable?

I went through quite a few including IDA and I think retdec though they pretty much do a similar jobs and both have their advantages in the stuff they output (ghidra seems to output the best pseudo c code though imho). However when I tried retdec I think it stumbles on the analysis of big files. What's the memory error you're getting? Is it getting stuck on the flow analysis?

Also something cool; the civ2 asm has its own debug methods, they're useful in figuring out bits and pieces. (There are string references to cpp files, a way to find what functions are responsible)

Yeah I was analysing civ2.exe. Managed to get a .c file with --backend-no-opts parameter I believe (not at my comp right now).
Nice with the asm find. Please do document here everything you find.

 

[joe@joesblog]

I was disassembling civ2.exe MGE with IDA. With default settings it gives a lot of incorrect standard library function names. After some analysis I guessed that civ2.exe was build using Visual C++ 4.xx. Then I got LIBCD file and used FLAIR tools to make my own signature library. With some additional fixes now it detects almost all library functions correctly.
Next big step is decompilation. And here is big challenge of decompiling try.. catch code or some vector constructors.. destructors. As it is using some not obvious exception handling structures, and Hex-Rays plugin doesn't generate clean code for them. Most times it fails with stack error. Actually official page says "exception handling is not supported".
There is good topic about it
http://www.openrce.org/articles/full_view/21
But that means too much manual work. Interesting that most game logic part uses simple c/c++ code. And complicated code is found mostly in multiplayer part.
Never used Ghidra. How does it deals with exception handling structures? Does it generates clean pseodo-code for that?

It handles it 'reasonably' well. though as well as can be expected without any debugging symbols or source code. Ghidra allows you to create your own structs, and i think import header files.

Whilst not explicitly decompiling to a try..catch it does handle stack unwiding. I've included a pastebin as an example (I think this is from the multiplayer code)
https://pastebin.com/GhXQDAyb

by looking at the flow of the code you can see how it was originally implimented

 

[axx]

Tried with SDL but didn't get further than intro screen.
Anyways if anyone is still interested, I'm re-writing the project with Eto forms so you can compile it not just on Windows, but on Linux and Mac also. Tried it on Ubuntu yesterday and it worked, but I've messed up some references in the meantime. I've also moved the engine part to a separate project, now you interact with it through UI projects.

 

[Rui_TNV]

Tried with SDL but didn't get further than intro screen.
Anyways if anyone is still interested, I'm re-writing the project with Eto forms so you can compile it not just on Windows, but on Linux and Mac also. Tried it on Ubuntu yesterday and it worked, but I've messed up some references in the meantime. I've also moved the engine part to a separate project, now you interact with it through UI projects.

Will this be a game similar with civ 2 test of time? And will it be possible to play on android?

 

[axx]

Will this be a game similar with civ 2 test of time? And will it be possible to play on android?

Since they are similar both Civ2 & ToT can be bundled into a single game (you'd have a switch to chose which one you want). As for Android it's too early to talk about it but Eto currently has an Android platform under development.

 

[CurtSibling]

I salute this project. A real massive goal, but a very worthy endeavour.
Breaking the limitations (like only 7 playable civs) of the original game would be great.

Following this thread with interest. And in a world were getting the original game code
seems impossible, the clone route might be the best way to unlock civ's true potential.

 

[XDXDXDXD]

Hi guys

I'd like to join the project. Not much of a programmer, but I can be a project manager and solve specific problems the project may have.

Languages I know - Python, C++

Other from that I can invest some reasonable resources into the project.

 

[Blake00]

Was anyone here part of the old Clash of Civilizations fan project? How far did it get? I've heard of it in passing but know very little about it due to being absent from the community in the mid 2000s. Had a look at the screenshots and it seems like they were going for a Civ2 like game although it looks more like a FreeCiv reinterpretation. Just found backup of their old website and was curious about it...
https://web.archive.org/web/20100901192522/http://clash.apolyton.net:80/frame

Final demo download still works so I might grab a copy as I'm gonna do a video tributing Civ2 like fan games (finished or not) at some point.

.

 

[axx]

How is the project coming along? Is there any changelog/to do list to monitor the progress / offer help?

Hi, sorry for the late reply, I don't check here nearly as often as I should. Just look at the commits here, it should be self-explanatory.
Another person (reubene on github) joined development and is amongst other things working on ToT support.
You can compile it and try loading a SAV and then report issues on github. Or help contributing if you're familiar with C#.

 

[axx]

Choose EtoFormsUI.WinForms as startup project, choose "Debug" in Solutions Configuration and press F5, it should work easiest of all in VS. Also make sure appsettings.json points to the correct Civ2 path.
Otherwise please write here what VS tells you or better yet make an issue in github.

 

[axx]

For now you can just load a game, work is being done on starting a new game atm.
The game is trying to get an active unit object but it cannot find one, probably because no units are active in game. It's a bug. In the meantime try loading a different SAV.

 

[Rui_TNV]

Is this game android friendly?

 

[axx]

Is this game android friendly?

Not atm.

 

[LuKo]

It seems that most of the game is not working for me but I was able to load one of my saves and I hope to do some testing in the future. The project looks very promising!

 

[CurtSibling]

Just wondering - How many civs are available for play? Are there more than 7 in game?

 

[axx]

@LuKo There's a ton of features missing. I'm currently dealing with basic stuff (moving units around, drawing map). Before moving on some more work needs to be done on popup boxes (dialogs), iirc there are >700 custom dialogs in the game!
@CurtSibling 7 currently. But the number of civs per se isn't a limitation. Like I mentioned in one of previous posts in the game loop I'm doing a foreach through all the civs, no matter how many there are. What would have to be done though is to decouple civs from certain rules, colors and such where everything is currently tied to number 7 (8 with barbs) in the game's .txt and .gif files. But I don't see that as a huge problem.