Is it possible to learn Japanese through playing games with Japanese game scripts?

Learning Japanese to import games and read manga is pretty much the worst reason to learn a language ever.

Also, no, if watching cartoons and playing video games really was the fast track to learning a new language, alot of people would be out of jobs.

You can read hiragana and katakana, but you won't know what you are reading unless you know the words. That's about as far as you'll get.

It's like being able to read english using phonics, but lacking vocabulary.