Coloured dice are like candy. They trigger the happy part of my brain. One Deck Dungeon has those dice and it uses them so well.
Every dungeon is built with one deck of cards, containing enemies and traps. You place four of them face down for the rooms you can enter. On your turn time passes: you discard some cards unseen from the deck so you won't encounter exactly the same cards every time. Then you open a door and see what's inside the room. You fight foes or disarm traps using your dice. Yellow for strength, pink for agility and blue for mana. Every card has coloured boxes on them, you roll your dice and try to fill them. After the encounter you'll pick your loot, by adding the card to your character. Improving your health, one of your abilities or learning a skill. Once you've had a few encounters, you can go exploring to have four new rooms available.
So you pick your character (mage, warrior, paladin, rogue, archer) and she'll go down in the cave, to fight a dragon. There are three levels in each dungeon, every one a little harder. Somewhere along the way your character dies. Except she doesn't. As this game should be played as a campaign. So somewhere along the way, she is knocked down and has to run. But now she's got a bit experience. Next time she enters the cave, she knows better which foes to take on, and which traps to overcome. She'll get further down the dungeon, before it's time to leave. She'll have enough experience to unlock a permanent skill. Now she comes prepared.
After you managed to slay the dragon, other - harder - dungeons and bosses will be waiting. But you'll have unlocked more permanent skills as well. It's a brilliant system. I played my 100th game last week, and I see no reason to quit.
Some people say you can lose a game by rolling low. Of course, everything is possible, but there is a lot of mitigation in One Deck Dungeon. You can exchange dice for ones of another colour, or even black "jokers". You can turn low numbers into higher ones or reroll them. You get loot, even if you lose a fight. The loot gives you a mitigation skill, extra dice to roll, or, if you need it, a potion. You can later replace items or skills for better ones and use the old ones as XP. As you level up inside a dungeon, you get more dice and potions. You can use potions to heal, so it's a valid strategy to lose some fights, just to get better loot, then heal. And you can always flee before a fight. You don't have to take on every single card.
Once you know the deck, you evaluate each encounter card and decide what to do. You go for the skills you need, the items you need in this particular dungeon. A bad roll won't kill you. Bad luck with the card draw may get you (when all four encounters are too hard), but in all my plays that only happened two or three times. Of course I still lost nearly half my games, but that's because you start out without any experience. You start every campaign with a loss or two and when you reach the harder dungeons, you'll probably lose again the first time you go in. I've also lost some more sessions when I played games on harder difficulty, or tried sub-optimal builds just for fun.
And if you don't like campaigns and want to play one-offs? Easy. Take on the dragon with a basic skill. Take on the next bosses with both a basic skill and one or two specialized skills. The final boss with a basic skill and a full specialization. Don't try to fight the Minotaur with a newbie character, then complain the game is too hard. It doesn't make sense.
Other ways to make the game easier are playing two-handed, or using the digital version (with an "undo" version that comes in real handy later on in the game when you can do transformations on already transformed dice). But for me the one-handed physical game is fine. Nothing beats rolling a handful of those coloured dice.