solution_steps.txt

1. First unzip the apk
2. Now grep to see where to find the flag. You will see mentions of it in the classes.dex file.
3. You will need to convert .dex to .jar or .java files. Find an online tool(http://apk-deguard.com, http://javadecompilers.com) or github repos to do that(dex2jar).
4. Study the code to find the hint to go to file C137 in earth dimensions. 
5. Get the hint to find the file names portal gun manual in the extracted apk folder.
6. Finally find a password protected zip file. Use the password hint provided in C137.java file to decrypt the zip file and get your flag.