Dwarf Tower is a turn-based tactics game of tower building and spellcasting. Each turn you develop your tower by placing blocks, constructing rooms, and play various spells. Your tower can have Libraries (store spells), Crystals (generate mana), Dwarf Dwellings (give you dwarves to repair the tower) and some other rooms.
Terribly sorry about the problems with online mode connectivity in v.1.4. It should be all fixed now, and you should be able to properly enjoy playing Dwarf Tower with your Steam friends.
The tradeoff is - the online mode is now only between Steam versions of the game. We'll be trying to make it intercompatible with Android and iOS in the future, but for now that's the most reliable and stable way of delivering you the best gameplay we can!
Inviting players to join game (from the friend list / steam overlay) should also be working properly now!