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Auto Patcher for game (Efficient Auto Updater)

I want an auto updater that detect modified game files (by comparing files on the client-side and a server) and only download modified files.
The scenario is that there's about one thousand clients in a network, that use same application. If a new version of the application is available, they all have to get the new version.
I see a www.aldera.to game if you install the files their Aelra_patcher application auto patch the files from the server side. It do the exact thing I want:Getting the newest files from server when the patcher is run. But the problem is that clients wrote in C#, and I can't use IcePatch2 inside my application.
So far, the best solution I found is to get .NET Application Updater Component and customize it to fit my needs. But I prefer a solution that dose not require me to maintain another application.
Any idea?

Managing file locks is fairly simple. The process should go something like this:
The game application downloads the installer, if there is any
The game application runs the installer and exits
The installer starts doing the work of updating files as needed. If any files are locked it may wait a short while and try again, or ask the user if it is ok to close the application that have locked the files.
But the topic of minimizing update time and bandwith is a fairly complex. You might want to read Raymon Chens articles on Windows Update Formats to get some appreciation for the various issues.
I'm not familiar with IcePatch2, but it seems to be a fairly generic file synchronization tool. This may be appropriate for your specific use case, but I would expect some use cases to benefit from a more specialized approach. You could for example use knowledge of things like file or resource versions to avoid much of the work a more generic tool has to do.

Looking to launch a local exe on a remote machine without having the resurces on the remote machine

So I have built some code, it's quite simple basically it stops all active input from keyboard and mouse until a text file of a certain name appears in the C:\Temp directory. It also has a manifest file to run it as administrator on start up.
So I found something that on the surface looks like it fulfils my needs of being able to do this task however upon running it I found out that the project has been compiled in x86 and does not run on my x64 machine. Here is the reference to the project if anyone would like to look into it, it's a very smartly designed piece of code that does an interesting objective. It also explains clearly enough what I am trying to accomplish.
So after implementing this (and failing) I have setup a couple other avenues to try, one is VBA through excel with the VBA copying itself to and from the machines in a list and running itself, then there is using VBS to write the entire code as a txt file on the target machine change the extension and then execute it remotely. I have just started researching these but I imagine the problems of running as an administrator amongst other things will crop up again to be dealt with. To be honest though I would really prefer to do this in C# only as that is the language I'm trying to go further in so I'm interested in this challenge. If anybody knows of a similar library of code or application I could look into to achieve what I'm trying I would appreciate being pointed in the right direction.
I would try and be more specific about what libraires/API's im trying to implement but the truth is I don't know what libraries I need to even interact with to get what I want. My goal is to have C# executable code on my machine and a tool that can run that executable on another machine.
Thanks

Thanks to the help in comments from #Nick.McDermaid I was able to correctly open and build the project I was trying to download. Unsure what caused the issue previously with me not being able to open and interact with the code but now I have it I shall pursue this avenue further to accomplish my goal.
As an addendum one other avenue I tried for executing code remotely was through VBS where I used
set svcproc=getobject("winmgmts:{impersonationLevel=impersonate}!\\"&MachineName & "\root\cimv2:win32_process")
scmd="""C:\Program Files\Internet Explorer\iexplore.exe"" -framemerging ""https://gifyu.com/images/Boo-Ghost-Gif.gif"""
'scmd="C:\Windows\notepad.exe"
iret=svcproc.create(scmd,null,null,pid)
set svcproc=nothing
to execute something that existed on the remote machine but I ran into a LOT of security policy issues where I could launch the process but I couldn't bring it to the foreground as the Malware tracker on the machine thought it was an attack and quashed it immediately.

Opening foreign file extensions, like in game files, How is it done?

In the sake of this game I'm modding at the moment, which has archives ending in ".rpf" (which is short for 'rage engine package file')
How exactly is it that programmers, can find ways to open these types of files/archives, without having access to the rage engine?
What would one need to know in order to even begin trying to open a foreign file extension? The files can be opened thanks to the OpenIV Team who created the program necessary for opening the files, but how exactly does a developer, figure out or even know where to start when it comes to developing an application that is to fulfill the task of opening another file?

It's called Reverse engineering
You look into file with hex editor, notice some texts, or numbers that look like offsets. You apply your own experience writing similar stuff, make some assumptions and check if it is correct for multiple entries, and so on and so forth.

There many ways to open such files.
First you can use specific programs to open them like OpenIV for RPF archive.
If you would try to Mod or write a cheat for example, most people disassemble the program or open them with a Hex-Editor.
Programs like HexEdit change the binary values of a program into hexadecimal numbers, for example the byte 10100101 into Hex 0xA5h (A5).
Another way is to disassemble the program. Programs like ollyDbg, IDA Pro or other disassemble the binary values into assembly-code. Now you're able to search for some offsets, adresses and texts and you can remove or edit them to let the program do what you want.
Some programs are able to generate a pseudocode to C or C# e.g. (.NET Reflector) which helps you to understand what the program do.
After you read for example some memory adresses and their offsets, you can change them in the disassemble program itself (JNZ (Jump if not Zero) to JMP (Jump) for example to jump directly in every case) and write these code on the executable or you can implement them in a own program which changes them or patch them.
That is the princip you looking up for to understand how the program does work and then you add some features of your own or write a complete new application to fulfill the task of opening any file. Like Vlad said thats simply called reverse engineering.

visual c# button opens file without specifying drive

I work for an IT company where we all carry around flash drives that have our most used programs on them.In my spare time I am hoping to create a "main menu" item that is kind of a fun and convenient way to access these files. I am working on creating this using Visual Studio 2013 and using visual C# windows forms. I have come across a snag however that I can't seem to find a workaround for. I am by no means fluent in C#, but I need to have a button on the windows form open a file without specifying what drive it comes from. I understand that I have to specify a path, but as these will be stored on the flash drives of myself and my coworkers I cannot foresee that the path will always begin with E:. Depending on what USB slot the drive is plugged into it could be N: or F: or the like. I have provided an example below:
Using what I currently know I am opening files using this line of code:
System.Diagnostics.Process.Start("C:/Users/Myname/Desktop/Asmodeus/Anti-Virus/Anti-Virus Installers/avast_free_antivirus_setup.exe");
Is there any way possible I can have the file open simply from
System.Diagnostics.Process.Start("Asmodeus/Anti-Virus/Anti-Virus Installers/avast_free_antivirus_setup.exe");
or something of that nature?
Thanks in advance.
There must have been some mis-communication when I asked my question previously. what I am looking to do is open an executable file via a button click on the windows form using a relative path. I am not able to specify the absolute path because the application will be run from a flash drive and therefore will change depending on what USB slot it is currently inserted into.
What I am hoping to accomplish is insert a line of code that will allow me to open an executable file that is located in the \bin\debug folder along with the application itself. I have a picture for clarification but apparently do not have enough reputation to post it. Thank you and sorry for the earlier confusion.

Usually you can just use Environment.GetFolderPath (MSDN) to give you what you need. It doesn't do absolutely everything, but if you need Desktop and the like, that is plenty.
Depending on the target version of .Net, the SpecialFolders exposed are not all there. It may turn out that you need more than they provide, but in your case it doesn't sound like it.
If there is more you need that is not covered in the default, check out this project. I'm sure there are others like it, but it does a little more than the default BCL version, using the API directly. It is at least something to read and learn (and translate from vb.. use an online translator, very quick). I haven't looked at it, but it seems like you are learning this c#/.net thingy, so it might be helpful
This article is about accessing Windows special folders.
These folders include your “Favorites”, “Cookies”, system libraries and the like.
Here is code, including a large number of constant definitions, plus documentation,
allowing access to and creation of these folders.

Limitations of a No-Install C# Application?

I'm using SharpDevelop to create a WinForm-based C# application. After studying my target audience, I believe it is in my best interest to use a no-install application. While creating my HelloWorld! program to get to know SharpDevelop (I have just switched from VBExpress), I found that the file it outputs is a .exe without any setup process. However, I'm worried that some of the features I want won't be compatible with this format. I don't want to get deep into this app and find out users are going to have to keep the program in the same directory as 548 other random files.
Here are the features I'm concerned about:
+Save user data (XML) in AppData.
+Access internet feeds (XML and/or JSON).
+Minimize to tray on close.
Also, are there any common pitfalls with this type of deployment method?
EDIT: I understand the enduser will need the .NET framwork for C# programs. I am not worried about this.

It will execute with the same privileges.
The only thing you will want to look out for is making sure the end user has the correct .NET framework installed since you don't have an installer to do that for you. But now reading the end of your message it appears you already have that covered.
If you are concerned about the deployment technique you can test it on a non-dev machine, though the results should be the exact same.