UNO Arena is a polished single-screen card battler around a green felt table. Player 1 chooses one or two AI rivals, matches the discard by color or symbol, plays action cards, calls UNO at one card, and races to 250 points. Desktop keeps the classic table spread, while mobile portrait rearranges opponents above the piles and preserves a clear bottom hand, Draw, UNO, and Sound control area for reliable touch play.