I don't think Payday uses the same version of the source engine as half life 2, but i'm sure it uses the same as Portal 2, so somebody could "port" that or left for dead 2.
Edit: nevermind
I think that you can restore the nand backup with HacDiskMount and Memloader, but if you are a noob I would wait until they implement restoring rawnand backups with sd cards smaller than 32gb in hekate
For som reason i cant seem to install any gamecube game with wup installer gx2. Howeber, it seems that nothing went wrong with the script.
And if wou ask, i am using mocha^_^