Phone slots are mobile-friendly casino games that use a random number generator...

https://mag-wiki.win/index.php/What_Is_ALTCHA_and_Why_Is_It_on_Sign-Up_Forms%3F

Phone slots are mobile-friendly casino games that use a random number generator (RNG) to ensure fair results. Before playing, check the game’s return-to-player (RTP) rate and volatility to match your style