This app was mentioned in 6 comments, with an average of 0.83 upvotes
Yomikata is the closest one that I've found, it doesn't have the srs features of rtk though, I've been mostly using anki myself, it's working pretty well, and it feels a bit boring.
This reply should be in the FAQ in my opinion. I feel like getting your head around the idea "This is hard and will take time" is a major hurdle for most people.
Like OP I started studying Japanese almost 10 years ago and had given up. This year I've picked it up again and it was painful. Once I got into a routine and found the tools/techniques that work for me I found my progress picked up and I started to enjoy studying Japanese. I know study whenever I have a free minute. Goodbye angry birds, hello life skill.
Don't be afraid to change up your study routine/practices. If you have been studying one way for a while and aren't happy with your progress, try something new and different.
If you're curious, my favorite tools right now are:
https://play.google.com/store/apps/details?id=com.jehutyno.yomikata&hl=en
*edit: formatting fixes. Konpai = reddit noob.
I like an app called Yomikata. I think it's only available for Android, though.
I use "Yomikata" to practice reading the characters when I have some free time (bus, train...). But for actual learning of grammar and vocabulary, I did not find a good app, I still use books and classes.
I have heard "Anki" is nice for remembering stuff, it is a flashcard system.
I have also seen good reviews of "HelloTalk". This is a language exchange app: you can meet people that learn your language and speak the one you are learning, and chat and correct each other.
Finally, this is more a website than an app, but I regularly use "Lang-8" where you can write a text in the language you are learning and native speakers comes to correct it for you.
You may also find information on /r/LearnJapanese.
There is something very similar to lingvist but not as extensive. Its an app call yomikata z like I said it's not as extensive but it's a good app