Recs.
Updated
Pixel Dungeon is a traditional roguelike* game with pixel-art graphics and simple interface.
Explore the depths of Pixel Dungeon, collect useful items, fight fierce monsters to find Amulet of Yendor (surprise!) - the ultimate artifact of this game world.
SpecsUpdate
Pros
Pro Maps and items are randomized allowing for lots of replayability
In a true roguelike fashion, levels are randomly generated each time a new game is started. And Pixel Dungeon goes one step further by randomizing effects of all items as well so it's impossible to tell if a dropped item will have a positive or a negative effect based on its sprite.
Pro Free and open source
No advertisements, no in-game store and available for free with code available on GitHub. There is a donation button in the app, which is why it is marked for containing in app purchases on the Play Store, but it is completely optional and in now was necessary for the game and all of its content.
Pro Great variation in items
Next to the typical selection of buffs, de-buffs, potions (that can be either consumed or thrown), weapons and armor (that have to identified and can carry with them bonuses and curses), there are also less common items like random teleportation scrolls, map reveals, etc.
Pro Challenging, fun gameplay that's easy to learn yet hard to master
Pixel Dungeon's gameplay is intuitive allowing for it to be easy to get into, but it's also very challenging quickly making the experience both rewarding and addictive.
Cons
Con Overly random
A lot of people see roguelike design as being based around randomness. It's actually a far more precise set of balances than that. A lot of roguelike developers shy way from "randomly generated content" in favor of the term "procedurally generated content." The reason for this is that a well designed roguelike is well balanced enough that if you lose or win, it's all because of the actions you took.
Pixel Dungeon has a habit of sometimes generating dungeons that are basically impossible and sometimes generating dungeons that are laughably easy.