Check the EXIF data of any images found inside using exiftool . Often, clues or parts of the flag are hidden in the Comment or Artist tags.
View the files inside the archive without extracting them to check for suspicious filenames or nested structures. unzip -l spookytimes_2-pc.zip File: spookytimes_2-pc.zip ...
Run strings on the binary files or images to look for human-readable text. strings image_name.png | grep "flag{" Check the EXIF data of any images found