CDOS, short for Crazy DOS and stylized as C:DOS, is a game themed after DOS, more specifically MS-DOS and multi-user Concurrent DOS (CDOS).
"Set in your average office from the late 80s, your task is to transfer the files in a floppy disk before your pesky coworkers crash the server."
Crazy DOS borrows mechanics from Crazy Eights and related games but what makes it a unique game is the use of real DOS commands (most cards represent both a file to "transfer" and a command you can "execute" to protect you from your opponents' actions or to speed up your shedding strategy) and a gameplay that simulates working with networked PCs.
The 18 commands in C:DOS work like they would on the computer: with MD you can create a new directory (pile), CD lets you change the current working directory (the pile where cards/files can be transferred to), CLS cleans your shell (the pile where you execute commands), with ATTRIB you can set files as hidden files (to transfer them face down and bluff), DEFRAG lets you see the contents of piles and reorder the cards/files to your liking...
C:DOS has an educational component in that it can be used to teach players basic computing in general and DOS in particular.
Removing the DOS and PC rules from the game, a deck of Crazy DOS can be used to play what is basically a slightly different version of Crazy Eights, making for a simpler party game that can be used to introduce players to Crazy DOS itself.