Extract the contents. If the .rar is password-protected, use tools like John the Ripper or hashcat to crack the password.
If this refers to the video game by Nerial , the "write-up" would focus on mastering card manipulation techniques like: Card-Shark.rar
For specific gameplay tutorials, Steam Community Guides offer extensive visual walk-throughs for every cheat in the game. Extract the contents
Check for files transferred over the network that could contain the final flag. Step 4: Finding the Flag Card-Shark.rar
Look for interesting protocols like HTTP, DNS, or ICMP.
If the flag is encoded, use the CyberChef tool to try Base64, Hex, or ROT13 decoding. Alternative: Video Game Walkthrough
Use ExifTool to look for hidden comments or GPS coordinates in the images.