How to sum up three file to one file.

[testacc123]

First of all:
My english isn't that well but i hope you understand what i mean ;D
And if this topic is illegal or something like this,please close the thread 'cause i don't know wether this is legal or illegal.

I downloaded a game from the internet.The game has 3 files with the same name and the same ending.(example: name.abc).But if i want to play it i need all files in one single file.(example: name.def).So the final file needs another ending as the former files.
So,can you tell me how to make three files to one file??

[buFFy!]

I guess you have to Mount it with Tools like Alkohol120% or Daemon Tools.
Tell me the exact name's of your files including the ending.
And maybe the name (maybe its a good one and i wanto play it too xD) of the Game?

Edit: If ur German, please write in German. Else write English