I'm a Java developer from seven years ago, mainly in web applications ... Is this enough to start in Game Industry?
If you have already published your own games on both Android and iOS, you are already in the industry. You have made and released games for sale.
So congratulations on that!
Put that stuff on your resume when you apply for jobs, nice and big at the top as "Completed Games" with all the store links.
What skills are the minimum required to start as junior game developer?
That is a very different question. The skills required depend on the job.
A company may be looking for a programmer with skills in C++, Java, Objective C, Flash/ActionScript, Python, HTML and JavaScript, or just about anything else.
If you built those games, then clearly you have at least the minimum skills needed to make games generally.
Having the skills does not mean you can skip HR filters -- that typically look for a combination of published games, employment history, and education. That process requires looking good on paper. If you want help with a resume or CV, post a link to it so people can critique and offer (hopefully constructive) opinions.
Having the skills does not mean you can skip interviews, where you are compared to other people. You might look good on paper and get the interview, but this process requires communicating effectively in person, and can be improved by being charismatic, being attractive, or having other traits.
Having the skills generally does not mean having the skills for a specific job, where your skills may not match. You may look good on paper, and you may be charming in person and have all the people skills, and you may be able to produce amazing Java code, but if you get into the interview and discover they want some very specific skill but you don't have it, that can be the end of the line.
Next, even if you look good on paper, and you present yourself well in the interview, and you have the specific skills you are looking for, you still might not be offered a job! You might be an amazing developer, but someone else may have applied and they seem even more amazing. That isn't because you're a bad programmer, but instead because you don't exist in a vacuum.
Finally, even if you do pass all those tests, your resume looks good and you get an interview, you get the interview and perform well, your skills match, and you are the one they want to hire, they still might not hire you! At that point you engage in salary negotiations, where you decide what you are worth and must be paid and also what you are willing to offer for that money. Sometimes companies refuse to pay what the worker thinks they are worth, sometimes the companies offer far below market rates, or they offer market rates to someone whose performance tends to deserve more money, and the job is not offered.
