Currently learning Japanese and this popped up on Humble Bundle.
I bought it a week ago and went from being unable to write any, and knowing bits of Hiragana and next to no Katakana to carefully being able to read both, and mostly write both from memory, and with about 50 Kanji characters under my belt and quickly gaining more. In a week.
Would recommend.
Good:
You can Kana - The best resource I've used yet for learning to both read and write Hiragana and Katakana, do this first
Learn Japanese to Survive! - This is in three parts, Hiragana, Katakana and Kanji, once you've finished the one above you can skip the first two and go straight to Kanji. Super cheesy but just good enough to play that you are motivated to finish it for the game element as well as the learning.
Influent - Basically a giant set of flash cards with a huge number of objects and systems for teaching verbs and adjectives. This actually works for many languages and is the version that includes them all.
Haven't tried:
Terra Alia - Going to try this next, unsure based on the reviews but indications point to it being a Google Translate simulator for Japanese
Nanotale - Not going to bother with this, it's for speed typing, but add your own review if you have played it in the comments
Playne - Meditation, not going to bother with this, but add your own review if you have played it in the comments
Epistory - Also not going to bother with this
The Textorcist - Bullet hell…exorcism learning. Not sure what to make of it, not going to bother, but add your own review if you have played it in the comments
If you're learning Japanese, then this has turned out to be an awesome bundle.