I took a Russian duolingo course, it was surprisingly thorough and well made. It teaches you the alphabet, basic phrases and a decent amount of grammar (verbs, tenses, prefixes), colloquial, etcetera. More than enough to get by in daily life, strike up a conversation and read some literature.

The website is very user-friendly, and the app has been designed specifically for mobile screens, so a lot less typing, and a lot more swiping.

It feels like a paid app, and I can't think of anything that comes close in value. If I were the CEO of RS I'd lose a lot of sleep over duolingo...