Ninja Dice is a lightweight, push-your-luck dice game that easily fits in the "filler" category of game. Game-play is stated in the rules as 15-30 minutes and I think this is a fair value.
The game begins with each player starting with 3 coins. The person to the left of the first player then creates a "house" by rolling 4 black dice. These dice have symbols representing locks, peasants, and guards to be beaten. Some dice have multiple symbols on some sides to make the challenge more difficult. The first player will then roll his 5 white skill dice in an attempt to beat the house challenges. Locks need a lock-pick, while peasants and guards can be either sneaked past (with a stealth symbol) or slain in true Ninja style with throwing stars. All symbols of a type have to be beaten by the same means. You can't fight some guards, but sneak past others. You can, however, sneak past the guards and kill the peasants (or vice-versa) if you like. There are 3 other types of symbol on the white skill dice as well. These are the Ninja face (wild card), block (more on this later) and the fortune symbol (4x multiplier).
This is the point where the game begins to shine in my opinion. On the fortune dice there is a a side-to-side arrow along 1 face of the dice which allows one of your other dice in front of this to become worth 4x the symbol shown. This is a mechanic I've never encountered before in a game, where not only does the face value of the dice matter, but it's orientation to the other dice too. If you don't get what you want, you can choose to re-roll as many dice as you choose to try and get what you need.
(Example of use of the fortune symbol - Green dice are eligible)
Every time the active player rolls, the other players also roll a die too. These dice will either allow them to steal coins from other players based on the orientation of the dice (arrow), protect themselve from theft (caught arrow), or take time (hourglass) from the active player. Each hourglass is locked in and is not re-rolled on subsequent rolls of the active player. If all 4 hourglasses show up before the active player has walked away, they get nothing. If they took the opportunity to get out when they could, they get coins for every house dice they beat as well as bonuses if they beat the entire house and/or if they only used stealth instead of combat.
Once everyone has had a turn at being the active player a second round begins with 5 house dice and then a third round with 6 dice. With the combination of multiple symbols on house dice and having more dice to beat than the active player, it soon becomes impossible to completely beat a house without using fortune multipliers. At the end of the game, the player with the most money is the winner.
The dice have nice heft to them, with good indentations so the markings won't rub off. The coins are plastic in gold, silver and copper. They could have gone with cardboard here, so this is a nice touch. The real hero of the game is the actual container. It's a soft cube that fits in the palm of your hand with the ninja face on the side of it and mask ties on the back. It really elevates this game away from the other small games on my shelf.
I really like Ninja Dice. With game-play that has all everyone involved even when it's not their turn, there is never a dull moment in this game. Being so compact as well, this lends the game to be taken anywhere with you. With the fun mechanics of the dice orientation mattering, there can be some real tense moments too as you push your luck trying to get that last elusive symbol before you run out of time. I heartily recommend Ninja Dice.
While I find the positional aspects novel, I feel the game really clicks once you add the locations pack. Instead of randomly rolling a house, you lay out cards based on the round that you pick to loot. These cards specify how many dice to roll, but may also have specific symbols or special rules, and a bonus coin value if you can complete the harder cards. More risk and reward.
The Ninja Dice: Kage Masters expansion is also fun because it introduces asymmetric ninja powers for each player, but the additional rules overhead might not be worth it depending on group and tastes.