If you've ever played NetHack, ADOM or Angband, then you have a fair idea of what to expect from Dweller. It's essentially a roguelike you can play on your mobile, as long as it has enough horsepower to run it.
There are two versions available: one with graphic tiles (pictured here), and the other with more traditional ASCII. Sufficed to say, the ASCII version stands a better chance of running without a hitch.
When you're bored on the train, it sure beats the heck out of Solitaire.